UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460



### MEMORANDUM

DATE: September 18,2013 OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION



### SUBJECT: Paclobutrazol : Preliminary Occupational and Residential Exposure / Risk

Assessment for Registration Review

PC Code: 12560 1

Decision No.: &./SS0" 1



### Petition No .: DP Barcode: D399496 Registration No .: Regulatory Action: Registration Review

Case No .: 7002 Risk Assessment Type: Single

Chemical/ Aggregate

TXRNo.:

MRIDNo

. : CAS No.: 76738.:.62-0

40 CFR:

FROM: Monica Hawkins, Ph.D., M

. P

. H.

, Environmental Hea l th Scientist 

### IV1

# TC**~** 

# K:-AllJ

Risk Assessment Branch 6 Jl

# ~ Health Effects Division (7509P)



### THROUGH: Fele cia Fort, Chief

# ~ 0 fA- 

# A

.

# ~ Risk Assessment Branch 6

# ~C:: Health Effects Division (7509P)

and

Charles Smith, Chief 

# C

Risk Assessment Branch I

Health Effects Di v ision (7509P)

TO: Khue Nguyen/Laura Parsons

Risk Management and Implementation Branch I

Pesticide Re-evaluation Division (7508P)

Page 1 of39

### INTRODUCTION

This memorandum contains HED's (Health Effec ts Division) occupational and residential

exposure and risk assessment required during registration review. As part of Registration
Review, the Pesticide Re-evaluation Division (PRD) of OPP re ques ted that HED conduct an occupational exposure/risk assessment for paclobutrazol for application as a foliar spray to turf (including parks, athletic fields, residential lawns, and golf courses), for application as a foliar

spray to ornamental plants in nurseries and greenhouses, use as a tree injection, use as a soil injection, use as a bulb soak treatment

, use as a pre-plant plug/liner soak, and for use as a seed

treatment (on cucurbit, pepper, and tomato seeds). As part of Registration Review, th e paclobu trazol hazard assessment was revisited by HED. Based on th e occupational exposure/risk assessment, HED has determined tha t there are potential occupational dermal risk

estimates for mixer/loader/applicators that use handheld equipment even with the use of personal protective equipment (PPE). There are also potential risk estimates of concern for workers entering nurseries to perform handset irrigation activities. The dermal plus inhala tion risk

estimates of concern for residential handlers is a concern for homeowners that are mixing/loading/applying paclobutrazol with a belly grinder. There are also potential residen t ial

dermal risk estimates for adults and children playing on treated turf for both liqui d and granular

formulations.

Pag e 2 of39Page 3 of 39 

### Table of Contents

1.0 EXECUTIVE SUMMARY

................................ ................................ ................................ . 4

2.0 HAZARD PROFILE

................................ ................................ ................................ ............ 6

3.0 USE PROFILE

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

4.0 OCCUPATIONAL EXPOSURE /RISK CHARACTERIZATION

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

4.1 Short

- and Intermediate

- Term Handler Exposure and Risk

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

4.2 Occupational Post

- application Exposure and Risk

................................ ........................ 21 5.0 RESIDENTIAL (NON

- OCCUPATIONAL) EXPOSURE

................................ .................... 24 5.1 Residential (Non

- Occupational) Handler Exposure and Risk

................................ ............. 25

5.2 Residential Post

- Application Exposure and Risk

................................ ............................... 27 5.3 Spray Drift

................................ ................................ ................................ .......................... 33Page 4 of 39



### 1.0 EXECUTIVE SUMMARY

Paclobutrazol, is a triazole plant growth regulator that slows vegetative growth by inhibiting gibberilin biosysthesis creating more compact plants.

Use Profile

There are a number of existing uses for paclobutrazol with formulations including liquids,

wetta ble powders, and granulars. Paclobutrazol is currently registered for use as a foliar spray for turf (including parks, athletic fields, residential lawns, and golf courses), a foliar spray for ornamentals in greenhouses and nurseries, as a bulb soak treatment, as a tree injection treatment,

as a soil injection, as a pre

- plant plug/liners treatment, and as a seed treatment for cucurbit, pepper, and tomato seeds.

Hazard Profile

Paclobutrazol is classified as Toxicity Category III for the acute oral route, Toxicity Category II

for the acute d ermal , a nd Toxicity Category III for the acute eye and skin irritation route. Quantification of short

- term (1

- 30 days) and intermediate

- term (1

- 6 months) dermal and

inhalation risks for paclobutrazol was performed using a developmental oral toxicity study. T he Lowest Observed Affect Level ( LOAEL ) from this study was 40 mg/kg/day based on renal dilation, hydroureter, and minor skeletal defects or variations . The No Observed Adverse Effect Level ( NOAEL ) from this study was 10 mg/kg/day. Based on a dermal abso rption stu dy in male rats, absorption of p aclobutrazol was deemed to be 24.5% after 24 hours. Since both the dermal and inhalation endpoints were based on the same toxicological effects, these route s may be

combined to result in a total margin of exposure ( MOE )

. Quantification of an incidental oral risk was performed using a 90

- day oral toxicity study. The LOAEL from this study was 93 mg/kg/day based on elevated liver weights and changes in clinical chemistry parameters

associated with the liver. The NO AEL from this study was 18.8 mg/kg/day

. Since the toxicological effects from the oral route of exposure are different than those from the dermal and inhalation routes of exposure, these routes should not be combined

. A target MOE of 1000 is considered adequate for all exposure scenarios (10X for interspecies extrapolation, 10X for intraspecies variability, and a 10X database uncertainty factor for lack of an acute and subchronic nuerotoxicity ).

There are no proposed or currently registered food uses for paclobutrazol. Carcinogenicity studies are not required for non

- food use chemicals. Carcinogenicity studies in mice and rats

are available. The Agency was unable to determine the potential carcinogenicity of paclobutr azol because the maximum tolerated dose (MTD) was not achieved in the 2

- year carcinogenicity/ chronic study in rats and the carcinogenicity/chronic study in mice. The carcinogenic potential will be re

- evaluated if the use pattern changes (i.e., food uses a re proposed).Page 5 of 39



### Occupational Handler

The occupational handler assessment was completed assuming the maximum label application rate for each crop. Based on the activity use pattern, the duration of exposure is expected to be

short

- term (1 to 30 d ays) and intermediate

- term (1 to 6 months). Long

- term exposures (greater than 6 months) are not anticipated based on the existing use pattern. For the dermal and

inhalation route s of exposure, the same points of departure were chosen for short

- term and

i ntermediate

- term exposures; therefore, risks are the same for all durations of exposure. Occupational handler exposures to the existing turf, ornamental, and tree uses of paclobutrazol may occur via the dermal and inhalation route. The short

- and intermed iate

- term risk estimates for most occupational handler scenarios do not exceed HED’s level of concern (MOEs ≥ 1000) at

some level of PPE . However, there are some handheld equipment scenarios that exceed HED’s

level of concern (MOEs < 1000) even with the us e of PPE.

Occupational handler exposures to the existing seed uses of paclobutrazol may occur via the dermal and inhalation route for both primary handlers (i.e., those who treat the seed in commercial seed treatment facilities) and secondary handlers (i.e., those w ho plant paclobutrazol treated seeds). The short

- and intermediate

- term risk estimates for all primary and secondary

handler scenarios do not exceed HED’s level of concern (MOEs ≥ 1000) at some level of PPE

.

Occupational Post

- application

Occupational po st

- application exposures to the existing uses of paclobutrazol may occur via the

dermal route. The results indicate that occupational post

- application risks, as calculated per HED default values, do not exceed HED’s level of concern (an MOE ≥ 1000) on day zero after application for all post

- application tasks that were assessed except for hand set irrigation in

nurseries

.

The restricted entry interval (REI) listed on the e xisting paclobutrazol labels are based on the acute toxicity of the technical materi al. Paclobutrazol is classified as Toxicity Category III for the acute oral route, Toxicity Category II for the acute dermal toxicity route, and Toxicity Category III for eye and skin irritation. It is not a skin sensitizer. In accordance with the Worke r Protection Standard (WPS), acute Toxicity Category I II and II chemicals require a 12

- or 24

- hour REI, respectively. Based on the acute dermal toxicity, the 12

- hour REI that appears on the current paclobutrazol labels may not be adequate and should be r evisited. Special consideration should also be given to use of hand set irrigation in nurseries.

Residential Handler

Although, paclobutrazol products do not appear to be specifically marketed towards residential handler use (i.e., homeowners); a residential handler assessment was performed to be protective of any such use. HED assumes that only short

- term exposures are applicable to residential risk assessments; ther efore, i ntermediate

- term and chronic exposures were not assessed for

residenti al handler risk assessments

. The residential handler assessment was completed assuming the maximum label application rate allowed for residential turfgrass. The combined

residential handler dermal plus inhalatio n MOEs do not exceed HED’s level of concern for allPage 6 of 39



### scenarios (i.e., MOEs ≥ 100 0 ) except for mixing/loading/applying with a belly grinder (MOE =

790 )

.

Residential Post

- application

HED determined that there is a potential for exposur e from entering paclobutrazol

- treated residential areas, such as lawns, sports fields, and golf courses that could lead to post

application e xposures to adults and children. A chemical

- specific turf transferable residue (TTR) study was available and was used to estimate transferable residues from turf treated with liquid formulations

.

Dermal post

- application risks were assessed for adults and children 1 < 2 years old while oral

post

- a pplication risks were assessed for children 1 < 2 years old. All adult and children mowing and golfing dermal risk estimates for both liquid and granular formulations do not exceed HED’s level of concern (MOEs ≥ 1000). All adult and children playing on t reated turf dermal risk estimates for both liquid and granular formulations exceed HED’s level of concern (MOEs < 1000). All children 1 < 2 years old oral non

- dietary ingestion risk estimates for both liquid and granular formulations do not exceed HED’s l evel of concern (MOEs ≥ 1000).

Review of Human Research

This exposure/risk assessment relies in part on data from studies in which adult human subjects were intentionally exposed to a pesticide or other chemical to determine their dermal and

inhalation exposure . These data, which include studies from the Pesticide Handlers Exposure

Database Version 1.1 ( PHED 1.1 ) ; the Outdoor Residential Exposure (ORETF) Database; the Agricultural Handlers Exposure Task Force ( AHETF ) database ; and the Agricultural Reent ry Task Force ( ARTF ) d atabase and a number of stu dies used in the 2012 S tandard Operating

Procedures for Residential Pesticide Assessment: Lawns/Turf are subject to ethics review

pursuant to 40 CFR Part 26, have received that review, and are compliant with applicable ethics requirements. For certain studies that review may have included review by the Human Studies Review Board. Descriptions of data sources as well as guidance on thei r use can be found at http://www.epa.gov/pesticides/science/handler

- exposure

- data.html and http://www.epa.gov/pesticides/science/post

- app

- exposure

- data.html

.

2.0 HAZARD PROF ILE

Paclobutrazol is classified as Toxicity Categor y III for the acute oral route , Toxicity Category II

for acute dermal , and Toxicity Category III for acute eye and skin irritation. It is not a dermal

sensitizer. Table 1 presents a summary of the acute toxicity information for paclobutrazol.Page 7 of 39 Table 1. Acute Toxicity of Paclobutrazol Technical Grade

Guideline No/Study Type MRIDs Results Toxicity Category

870.1100 Acute Oral (97% ai)

Alderley Park Rat 00117478 (1983) LD 50 = 1954 mg/kg (M) 1336 mg/kg (F) III

870.1100 Acute Oral (97% ai)

Alderley Park Mouse 00117478 (1982) LD 50 = 490 mg/kg (M) 1219 mg/kg (F) II

870.1100 Acute Oral (97% ai) Dunkin Hartley Albino Guinea pig 00117478 (1982) LD 50 = 542 mg/kg (M) >400 and <640 mg/kg (F) III

870.1100 Acute Oral (97% ai)

NZW Rabbit 00117478 (1982) LD 50 = 835 mg/kg (M) 937 mg/kg (F) III

870.1200 Acute Dermal (97% ai)

Alderley Park Rat 00117478 (1982) LD 50 = >1000 mg/kg (M F) II

870.1200 Acute Dermal (97% ai)

NZW Rabbit 00117478 (1982) LD 50 = >1000 mg/kg (M F) II

870.1300 Acute Inhalation (97% ai)

50% ai Alderley Park Rat 00117482 (1982) LC 50 = >766 mg/m 3 (M)

359

- 766 mg/m 3 (F) II

870. 2400 Primary Eye Irritation ( 97% ai)

NZW Rabbit 00117479 (1982) 5/6 rabbits with unwashed eyes had slight corneal opacity,

which cleared within 7 days; 3/6 rabbits with washed eyes had slight redness of the conjunctiva, with some chemosis and discharge, which was not apparent by 3 days. III a

870.2500 Primary Skin Irritation

(97% ai) NZW Rabbit 00117479 (1982) Mild irritation that persisted for

72 hours III

870.2500 Primary Skin Irritation

( 97% ai) Alderley Park

Albino Rat 00117479 (1982) 3/5 M showed erythema; 2/5 (F) showed desquamation and scabbing. Effects did not persist in either sex. III

870.2600 Dermal Sensitization (Guinea

pig) Dunkin Hartley Albino 00117479 (1982) Not a skin sensitizer

a Reclassified in 1995, based on additional data provided by the registrant (HED Document 011460).



### Short

- term Dermal : Quantification of dermal risks was performed using a developmental rat study with a NOAEL of 10 mg/kg/day based on renal dilation, hydroureter and minor skeletal defects or variations (LOAEL = 40 mg/kg/day)

. Since an oral dose was selected, a dermal absorption factor of 24.5% sh ould be used in estimating dermal risks (see Section 3.2.1). A Margin of Exposure (MOE) of 1000 is required which includes interspecies extrapolation (10X), intraspecies variability (10X), and the database uncertainty factor for lack of a neurotoxicity

ba ttery.

Short

- term Inhalation : Quantification of inhalation risks was performed using a developmental rat study with a NOAEL of 10 mg/kg/day based on renal dilation, hydroureter and minor skeletal defects or variations (LOAEL = 40 mg/kg/day)

. Since an oral dose was selected absorption via inhalation is presumed to be equivalent to oral absorption. A MOE of 1000 is required which includes to account for interspecies extrapolation (10X), intraspecies variability (10X), and the

database uncertain ty factor for lack of a neurotoxicity battery.Page 8 of 39



### Short

- term Incidental Oral : Quantification of incidental oral ingestion risks was performed using

a 90

- day oral rat study with a NOAEL of 18.8 mg/kg/day based on elevated liver weights, and changes in clinica l chemistry parameters associated with the liver (LOAEL = 93 mg/kg/day) . A MOE of 1000 is required which includes interspecies extrapolation (10X), intraspecies variability (10X), and the database uncertainty factor for lack of a neurotoxicity battery.

E xposures from the short

- term and intermediate

- term dermal and inhalation routes were combined because the points of departure for these routes are based on the same toxicological

effects. Exposures from the short

- term and intermediate

- term oral route w ere not combined with the dermal and inhalation routes of exposure because the points of departure for these routes are

not based on the same toxicological effects.

There are no proposed or currently registered food uses for paclobutrazol. Carcinogenicity studies are not required for non

- food use chemicals. Carcinogenicity studies in mice and rats are

available. In 1994, the RfD Peer Committee evaluated the potential carcinogenicity of paclobutrazol (TXR 0011081). At that time it was determined that the Agency was unable to determine the potential carcinogenicity of paclobutrazol because the maximum tolerated dose (MTD) was not achieved in the 2

- year carcinogenicity/c hronic study in rats and the carcinogenicity/chronic study in mice. The carcinogenic potential will be re

- evaluated if the use pattern changes (i.e., food uses are proposed).

The Agency’s level of concern for risks (i.e., target level for MOEs) is defined by the uncertainty factors that are applied to the assessment. The Agency typicall y applies a factor of 10X to account for interspecies extrapolation to humans from the animal test species and another factor

of 10X to account for intra

- species sensitivit y

. In the case of paclobutrazol, a 10x database uncertainty factor (UF DB 

### ) has also been applied due to lack of a cute and subchronic neurotoxicity studies . These studies are required for paclobutrazol because p aclobutrazol is a

member of the triazole che mical class which in general appear to be neurotoxic . T here is not sufficient data that evaluated the neurotoxic potential of paclobutrazol. As a result, t he total uncertainty factor that has been applied to occupational and residential risk assessments i s 100 0

for short

- and intermediate

- term dermal, inhalation and incidental oral exposures.

Table 2 presents the selected points o f departure for Paclobutrazol

.Page 9 of 39

Table 2 : Summary of Revised Toxicological Points of Departure and Endpoints for Paclobutrazol from Supplemental Data Provided By the Registrant (2007) 1

Exposure/

Scenario Point of

Departure Uncertainty

Factors Level of Concern for

Risk Assessment Study and Toxicological Effects

Acute Dietary No endpoints identified from the available developments toxicity studies (rat and rabbit) appropriate for an acute dietary assessment for paclobutrazol.

Incidental Oral

Short

- Term (1

- 30 days) NOAEL =

18.8 mg/kg/day UF A =10x

UF H =10x

UF D B = 10x Residential LOC for

MOE = 1000 Occupational = NA 90

- Day Oral Toxicity Study in

Rats

MRID 00132689 LOAEL = 93 mg/kg/day, based on elevated liver weights, and changes in clinical chemistry parameters associated with the

liver Incidental Oral

Intermediate

- Term (1

- 6 months)

Dermal

Short

- Term (1

- 30 days) Oral NOAEL =

10 mg/kg/day

(Dermal Absorption rate

= 24.5% ) UF A =10x

UF H =10x

UF D B = 10x Residential/

Occupational LOC

for MOE = 1000 Developmental (Rat) Toxicity Study

MRID 00143158 LOAEL = 40 mg/kg/day, based on renal dilation, hydroureter

and minor skeletal defects or

variations Dermal

Intermediate

- Term (1

- 6 months)

Inhalation Short

Term (1

- 30 days) Oral NOAEL =

10 mg/kg/day) UF A =10x

UF H =10x

UF D B = 10x Residential/

Occupational LOC

for MOE = 1000 Developmental (Rat) Toxicity Study

MRID 00143158 LOAEL for this study is 40 mg/kg/day, based on renal dilation, hydroureter and minor

skeletal defects or variations Inhalation

Intermediate

- term (1

- 6 months)

Cancer (oral, dermal, inhalation) Not required for non

- food use pesticides.

Explanation of Abbreviations: Point of Departure (PoD) = A data point or an estimated point that is derived from

observed dose

- response data and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UF A = extrapolation from animal to human (interspecies).

UF H = potential variation i n sensitivity among members of the human population (intraspecies). UF D B = database uncertainty, lack of neurotoxicity (acute and subchronic)studies. MOE = margin of exposure. LOC = level of

concern.



### 3.0 USE PROFILE

Paclobutrazol is currently registered for use as a foliar spray to turf (including parks, athletic fields, residential lawns, and golf courses)

, ornamental plants in nurseries and greenhouses, as a tree injection, as a soil injection, as a bulb soak treatment, as pre

- plant plugs/liners, and as a seed treatment (on cucurbit, pepper, and tomato seeds). Specific details related to the existing use

p attern are s ummarized in Table 3

.Page 10 of 39 Table 3: Paclobutrazol Use Patterns and Formulations

Formulation Use Sites Maximum Application Rate Application

Equipment REI Notes

Soluble

Concentrate Turf 0.75 lb ai/A Ground and

handheld 24 hrs or 12

hrs depending

on label Although paclobutrazol turf

products do not appear to be specifically marketed towards residential handler use (i.e., homeowners); residential handler

use was assumed to be protective of any such use

Granul ar Turf 0.5 lb ai/A Ground and

handheld 12 hrs Although paclobutrazol turf products do not appear to be specifically marketed towards residential handler use (i.e., homeowners); residential handler

use was assumed to be protective of any such use

Soluble

Concentrate Tree Injection

(So il injection at base of tree) 0.352 lb ai/tree Soil injection equipment N/A

Emulsifiable

Concentrate Pre

- plant

plugs/liners 0.0000 51 lb ai/gal Plug/liner soak N/A

Emulsifiable

Concentrate Bulbs 0.00255 lb ai/gal Bulb soak N/A Application rate represents highest application rate for a bulb (freesia)

Emulsifiable

Concentrate Ornamental

Plants in

Greenhouses

and Nurseries 0.59 lb ai/A Ground and

handheld 12 hours Application rate represents highest application rate for an ornamental (chrysanthemu ms)

Soluble

Concentrate Tree Injection

(8 inch tree) 0.0099 lb ai/tree Pressurized injection system

N/A Application rates on labels are presented for multiple diameter trees; two application rates were selected to be representative of

those on the labels Tree Injection (35 inch tree) 0.07 lb ai/tree Pressurized injection system

Soluble

Concentrate Cucurbit Seed 0.00027 lb ai/lb seed Commercial seed treatment equipment N/A On

- farm seed treatment is prohibited Tomato Seed 0.00414 lb ai/lb seed Pepper Seed 0.00247 lb ai/lb seed

Wettable

Powder Tree Injection

(6

- 16 inches in diameter) 0.000059 lb ai/tree Pressurized injection system

N/A Application rates on labels are presented for multiple diameter trees; two application rates were

selected to be representative of

those on the labels Tree Injection (>16 inches in diameter) 0.00024 lb ai/tree Pressurized injection system



### 4.0 OCCUPATIONAL EXPOSURE /RISK CHARACTERIZATION

4.1 Short

- and Intermediate

- Term Handler Exposure and Risk

Short

- /Intermediate

- Term Handler Risk for Turf, Ornamental, and Tree Uses

Based on the anticipated use patterns and current labeling, types of equipment and techniques that can potentially be used, occupational handler dermal and inhalation exposure is expected

from the existing uses. The quantitative exposure/risk assessment d eveloped for occupational handlers is based on the following scenarios:Page 11 of 39



### Mixing/loading liquids for groundboom applications Mixing/loading wettable powders for tree injections Mixing/loading granules for open cab solid broadcast spreader applications Mixing /loading liquid concentrations via dip Applying sprays for open cab groundboom equipmen t Applying granules for open cab solid broadcast spreader Loading/applying granules for belly grinder applications Loading/applying granules for pus h type spreader applications Mixing/loading/applying liquids for backpack sprayer applications Mixing/loading/applying liquids for manually pressurized handwand applications Mixing/loading/applying liquids for mechanically pressurized handgun sprayer applic ations

For pesticide handlers, HED presents estimates of dermal exposure for “baseline” (i.e., workers wearing a single layer of work clothing consisting of a long sleeved shirt, long pants, shoes plus socks and no protective gloves), as well as for “base line” and the use of protective gloves or other PPE, as might be necessary. The paclobutrazol product labels direct mixers, loaders, applicators and other handlers to wear long

- sleeved shirt and long pants, chemical

- resistant gloves, and shoes plus socks

. In addition, some of the labels also state that chemical

- resistant aprons should also be used.

It is the policy of HED to use the best available data to assess handler exposure. Sources of generic handler data, used as surrogate data in the absence of chemical

- specific data, include the PHED 1.1, the AHETF database, the ORETF database, or other reg istrant

- submitted occupational exposure studies. Some of these data are proprietary (e.g., AHETF data), and subject to the data protection provisions of FIFRA. The standard values recommended for use in predicting handler exposure that are used in this a ssessment, known as “unit exposures”, are outlined in the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (http://www.epa.gov/opp00001/science/handler

- exposure

- table.pdf), which, along with additional information on HED policy on u se of surrogate data, including descriptions of the various sources, can be found at http://www.epa.gov/pesticides/science/handler

- exposure

data.html

.

Typically, HED completes short

- and intermediate

- term assessments for occupational scenarios in all cases because these kinds of exposures are likely and acceptable use/usage data are not available to justify deleting intermediate

- term scenarios. Based on use data and label

instr uctions, HED believes that occupational exposures may occur over a single day or up to weeks at a time for many of the use

- patterns and that intermittent exposure over several weeks may also occur. Some applicators may apply these products over a period o f weeks, because they are commercial applicators who are completing multiple pesticide applications for multiple clients. Long

- term exposures are not expected; therefore, a long

- term assessment was not
conducted.

The daily areas treated or amounts hand led were defined for each handler scenario (in appropriate units) by determining the amount that can be reasonably treated by an individual in a single day. When possible, the assumptions for daily areas treated or amounts handled are takenPage 12 of 39



### from the HED’s ExpoSAC Policy #9 .1 : “Standard Values for Daily Acres Treated in Agriculture”. Values used for area treated or amount handled include :

40 acres for groundboo m application for golf courses and nurseries ;
4 0 acres for tractor drawn spreader application for golf courses ;
50 trees/day for tree inject ion applications (see note below) ;
5 0 trees/day for soil injection applications (see note below) ; 100 and 1000 gallons for mixing/loading liquids concentrations via dip; 5 acres for mixing/loading/applying with a mechanica lly pressurized handgun sprayer to turf and golf courses and 25 acres to nurseries and greenhouses ; 5 acres for mixing/loading/applying with a ma nually pressurized h andw and to nurseries and greenhouses ; 5 acres for mixing/loading/ap plying with a backpack sprayer to turf, golf courses, nurseries, and greenhouses ; and

5 acre s for push

- type spreader application to turf and golf courses

.

Note: HED received written information from several paclobutrazol registrants that for occupational applicators, about 50 trees per day are treated for tree injection applications and soil injection applications. The data ranged from 10 trees per day to 70 trees per day . HED selec ted 50 trees per day for tree and soil injection applications because it wa s the most typical number

from the available information

.

Daily dermal or inhalation handler exposures are estimated for each applicable handler task with

the a pplication rate, the amount handled or area treated in a day, and the applicable dermal or

inhalation unit exposure using the following formula:

Daily Exposure = Unit Exposure x Application Rate x Daily Area Treated

Where:

Daily Exposure = Amount (mg/day) deposited on the surface of the skin that is available for

d ermal absorption or amount inhaled that is available for inhalation absorption; Unit Exposure = Unit exposure value (mg/ lb ai) ; Application Rate = Normalized application rate b ased on a logical unit treatment, such as acres (A);

and Daily Area Treated = Normalized application area based on a logical unit treatment such as acres (A/day).



### The daily dermal or inhalation dose is calculated by normalizing the daily expos ure by body weight and adjusting, if necessary, with an appropriate dermal or inhalation absorption factor using the following formula:

Average Daily Dose = Daily Exposure x Absorption Factor / Body Weight

Where:

Average Daily Dose = Absorbed dose received from exposure to a pesticide in a given scenario (mg/kg/day); Daily Exposure = Amount (mg/day) deposited on the surface of the skin that is available for

d ermal absorption or amount inhaled that is available for inhalation ab sorption;Page 13 of 39

Absorption Factor = A measure of the amount of chemical that crosses a biological boundary such as the skin or lungs (% of the total available absorbed); and Body Weight = Body weight determined to represent the population of interest i n a risk assessment (kg).



### Margin of Exposure (MOE): The daily dermal dose and daily inhalation dose rec eived by occupational handlers are compared to the appropriate point of departure (i.e., N OAEL) to assess the risk to occupational handlers for each exposure route. All MOE values are calculated separately for dermal and inhalation exposure lev els using the following equation :

MOE = NOAEL (mg/kg/day) / Average Daily Dose (mg/kg/day)

Where:

MOE = Margin of exposure value used by HED to represent risk or how close a chemical exposure is to being a concern (unitless),

ADD = Average daily dose is the absorbed dose received from exposure to pesticide (mg/kg/day)

NOAEL = No Observable Adver se Effect Level (mg/kg/day)



### Combined Risks: Dermal and inhalation risks for short

- and intermediate

- term exposures were combined in this assessment, since the toxicological effects for the dermal and inhalations routes

were the same. Dermal and inhalati on risks were combined using the following equation:

Total MOE = 1/ ((1/ Dermal MOE) + (1/Inhalation MOE))



### The s hort

- and intermediate

- term risk estimates for occupational hand lers are included in Table

4

. The short

- and intermediate

- term risk estimates for most occupational handler scenarios do

not exceed HED’s level of concern (MOEs ≥ 1000) at some level of personal protective equipment (PPE) . However, there are some handheld equipment scenarios that excee d HED’s

level of concern (MOEs < 1000) even with the use of PPE.Page 14 of 39 Table 4 . Occupational Handler Exposures and Risks for Paclobutrazol Turf, Ornamental, and Tree Uses

Activity Use Site PPE

- G

Dermal

Unit Exposure (mg/lb ai) a PPE

- DL

Dermal

Unit Exposure (mg/lb ai) a Baseline

Inhalation

Unit Exposure (mg/lb ai) a Application

Rate b Area

Treated Daily c PPE

- G PPE

- G, DL Baseline Inhalation Total MOE ( PPE

- G +

Baseline

Inhalation ) Total MOE

( PPE G

- DL

+ Baseline

Inhalation ) Dermal

Dose (mg/kg/day) d MOE f Dermal

Dose (mg/kg/day) d MOE f Dose (mg/kg/day) e MOE g

Mixing/Loading Liquids Groundboom Applications on

Ornamentals in

Nurseries

0.0376 0.0291 0.000219 0.59 lb ai/A 40 A 0.0027 3,700 0.0021 4,800 0.000065 150,000 3,600 4,600

Groundboom Applications on Golf

Courses 0.75 lb ai/A 40 A 0.0035 2,900 0.0027 3,700 0.000082 120,000 2,800 3,600

Tree Injection (8 diameter Inch Trees) 0.0099 lb

ai/tree 50 trees 0.000057 180,000 0.000044 230,000 0.0000014 7,400,000 170,000 220,000

Tree Injection (35 diameter Inch Trees) 0.07 lb ai/tree 50 trees 0.0004 25,000 0.00031 32,000 0.0000096 1,000,000 24,000 31,000

Tree Soil Injection 0.352 lb

ai/tree 50 trees 0.002 4,900 0.0016 6,400 0.000048 210,000 4,800 6,200

Dips for Plug/Liner

Soaks 0.000051 lb ai/gal 100 gals 0.00000059 17,000,000 0.00000045 22,000,000 1.40E

- 08 720,000,000 17,000,000 21,000,000

0.000051 lb ai/gal 1000 gal s 0.0000059 1,700,000 0.0000045 2,200,000 1.40 E

- 07 72,000,000 1,700,000 2,100,000

Dips for Bulb Soaks (Freesia) 0.00255 lb ai/gal 100 gals 0.000029 340,000 0.000023 440,000 0.0000007 14,000,000 330,000 430,000

0.00255 lb ai/gal 1000 gals 0.00029 34,000 0.00023 44,000 0.000007 1,400,000 33,000 43,000

Mixing/Loading Wettable

Powders Tree Injection (6

- 16 inches in diameter) 0.17 0.13 0.043 0.000059 lb

ai/tree 50 trees 0.0000015 6,500,000 0.0000012 8,500,000 0.0000016 6,300,000 3,200,000 3, 600,000

Tree Injection (>16 inches in diameter) 0.00024 lb

ai/tree 50 trees 0.0000062 1,600,000 0.0000048 2,100,000 0.0000065 1,600,000 790,000 890,000

Loading Granulars Tractor Drawn Spreader Applications on Golf

Courses 0.0069 0.0034 0.0017 0.5 lb ai/A 40 A 0.00042 24,000 0.00021 48,000 0.00043 24,000 12,000 16,000

Applying Liquid Sprays

via Grounboom Golf Courses

0.0161 0.0126 0.00034 0.75 lb ai/A 40 A 0.0015 6,800 0.0012 8,600 0.00013 78,000 6,200 7,800

Ornamentals in

Nurseries 0.59 lb ai/A 40 A 0.0012 8,600 0.00091 11,000 0.0001 100,000 7,900 9,900Page 15 of 39 Table 4 . Occupational Handler Exposures and Risks for Paclobutrazol Turf, Ornamental, and Tree Uses

Activity Use Site PPE

- G

Dermal

Unit Exposure (mg/lb ai) a PPE

- DL

Dermal

Unit Exposure (mg/lb ai) a Baseline

Inhalation

Unit Exposure (mg/lb ai) a Application

Rate b Area

Treated Daily c PPE

- G PPE

- G, DL Baseline Inhalation Total MOE ( PPE

- G +

Baseline

Inhalation ) Total MOE

( PPE G

- DL

+ Baseline

Inhalation ) Dermal

Dose (mg/kg/day) d MOE f Dermal

Dose (mg/kg/day) d MOE f Dose (mg/kg/day) e MOE g

Appyling Granulars via Tractor Drawn Spreader Golf Courses 0.0072 0.0042 0.0012 0.5 lb ai/A 40 A 0.00044 23,000 0.00026 39,000 0.0003 33,000 13,000 18,000

Mixing/Loading/Applying Liquids via Backpack Sprayer Turf

8.26 4.12 0.00258 0.75 lb ai/A 5 A 0.095 110 0.047 210 0.00012 83,000 110 210

Golf Course 0.75 lb ai/A 5 A 0.095 110 0.047 210 0.00012 83,000 110 210

Drench Tree Treatments (8 inch Tree) 0.07 lb ai/tree 50 trees 0.089 110 0.044 230 0.00011 89,000 110 230

Drench Tree Treatments (35 inch Tree) 0.31 lb ai/tree 50 trees 0.39 26 0.2 51 0.0005 20,000 25 51

Foliar Sprays on

Ornamentals in

Nurseries and

Greenhouses 11.2 6.23 0.14 0.59 lb ai/A 5 A 0.1 99 0.056 180 0.0052 1,900 94 160

Mixing/Loading/Applying Liquids via Manually

Pressurized Handwand Foliar Sprays on

Ornamentals in

Nurseries and

Greenhouses

0.43 0.365 0.03 0.59 lb ai/A 5 A 0.0039 2,600 0.0033 3,000 0.0011 9,000 2,000 2,300

Drench Tree Treatments (8 inch Tree) 0.07 lb ai/tree 50 trees 0.0046 2,200 0.0039 2,600 0.0013 7,600 1,700 1,900

Drench Tree Treatments (35 inch Tree) 0.31 lb ai/tree 50 trees 0.02 490 0.017 580 0.0058 1,700 380 430

Mixing/Loading/Applying Liquids via Mechanically

Pressurized Handwand Turf 0.88 0.45 0.0019 0.75 lb ai /A 5 A 0.01 990 0.0052 1,900 0.000089 110,000 980 1,900

Golf Course 0.75 lb ai/A 5 A 0.01 990 0.0052 1,900 0.000089 110,000 980 1,900 Foliar Sprays on

Ornamentals in

Nurseries 0.39 0.29 0.0039 0.59 lb ai/A 25 A 0.018 570 0.013 760 0.00072 14,000 550 720

Foliar Sprays on

Ornamentals in

Greenhouses 2.5 1.6 0.12 0.59 lb ai/A 25 A 0.11 89 0.072 140 0.022 450 74 110

Loading/Applying

Granulars via Push

- type Spreader Turf

0.24 0.13 0.01 0.5 lb ai/A 5 A 0.0018 5,400 0.001 10,000 0.00031 32,000 4,700 7,600

Golf Course 0.5 lb ai/A 5 A 0.0018 5,400 0.001 10,000 0.00031 32,000 4,700 7,600

a. Unit Exposures taken from Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (http://ww w.epa.gov/opp00001/science/handler

- exposure

- table.pdf) b. Application rates = maximum application rates from labels. c. Amount handled per day values are HED estimates of acres treated or gallons applied per day based on Exposure SAC SOP #9 “Standard Values for Daily Acres Treated in Agriculture,” industryPage 16 of 39 sources, and HED estimates. d. Dermal Dose (mg/kg/day) = Dermal Unit exposure (mg/lb ai) x App Rate x Area Treated x %Absorption (24.5% dermal) / Body weight (80 kg).

e. Inhalation Dose (mg/kg/day) = Inhalation Unit exposure (mg/lb ai) x App Rate x Area Treated x %Absorption (100% inhalation ) / Body weight (80 kg).

f

. Dermal MOE = NOAEL (10 mg/kg/day) / Dermal Dose (mg/kg/day)

g. Inhalation MOE = NOAEL (10 mg/kg/da y) / Inhalation Dose (mg/kg/day)Page 17 of 39



### Short

- /Intermediate

- Term Handler Risk for Seed Treatments

Paclobutrazol is currently registered for commercial seed treatment use on tomato, pepper, and

cucurbit se eds (see Table 3). The paclobutrazol labels do not permit on

- farm seed treatment. Based on the existing seed treatment use pattern, t here is a potential for exposure to paclobutrazol to primary handlers (i.e., activities related to treating the seed) and secondary handlers (i.e., planting t reated seed). Primary and secondary handler exposure is expected to be

short

- or intermediate

- term in duration based on the information provided on the existing label s

. The short

- and intermediate

- term toxicological endpoints are the same for the respect ive routes of exposure; therefore, the estimates of risk for short

- term duration exposures are protective of

those for intermediate

- term durations.

Primary Handler (Treating Seed)

Potential primary occupational handler exposure scenarios from the use of paclobutrazol as a commercial seed treatment include:

Mixing, loading, applying liquid formulations; Bagging treated seed; Sewing bags; and Multiple activities.

Typically, for large

- scale commercial seed treatments, workers perform only those specific individual tasks listed above; however, it is assumed that workers also may perform multiple activities throughout the day. As a result a “multiple activities” scen ario (i.e. where one worker performs all seed treatment tasks such as loading/applying, sewing, bagging, cleaning, calibration, repair, forklift driver, etc.) was addressed. No assessment was performed for on

farm seed treatment as t he paclobutrazol labels do not permit on

- farm seed treatment.

Secondary Handler (Planting Treated Seed)

Potential secondary occupational handler exposure scenarios from the use of paclobutrazol as a commercial seed treatment include planting treated seed.

It is the policy of HED to use the best available data to assess handler exposure. Sources of generic handler data for seed treatment are incorporated in HED ExpoSAC Policy 14: SOPs for

Seed Treatment. The amount of active ingredient handled depen ds on the application rate (lb ai/lb seed or lb ai/seed), the pounds of seed treated in a day, and the pounds of seed that can be planted in a day, all of which vary depending upon the seed type. Values for the amount of seed treated and planted per day w ere obtained from HED ExpoSAC Policy 15.

Summaries of the risk estimates for primary and secondary h andlers are included in Tables 5 and

6

. The short

- and intermediate

- term risk estimates for all primary and secondary handler

scenarios do not exceed HED’ s level of concern (MOEs > 1000) at some level of PPE

.Page 18 of 39

Table 5 : Summary of Short

- and Intermediate

- Term Occupational Handler Exposure and Risk Estimates for Paclobutrazol Seed Treatment Uses

Seed Type lbs seed

treated/day

a Application

Rate b

(lb ai/lb seed) Amount

Handled per day (lb ai/day) Baseline

Dermal Unit Exposure c (mg/lb ai) Baseline

Inhalation Unit Exposure c (ug/lb ai) PPE

- G

Dermal

Unit Exposure c (mg/lb ai) Baseline

Dermal

MOE d PPE

- G

Dermal

MO E d Baseline

Inhalation

MOE e Total

Baseline

MOE Total MOE

(Baseline

Inhalation + Gloves)

Loader/Applicator

Cucurbit (Cucumber) 5512 0.000229 1.3

No Data 0.34 0.023 N/A 110000 1900000 N/A 100000

Cucurbit (Cantaloupe) 5512 0.00027 1.5 N/A 95000 1600000 N/A 90000

Cucurbit (Pumpkin) 5512 0.000107 0.6 N/A 240000 4000000 N/A 230000

Cucurbit (Squash) 5512 0.000172 0.9 N/A 150000 2500000 N/A 140000

Cucurbit (Watermelon) 5512 0.000157 0.9 N/A 160000 2700000 N/A 150000

Pepper 5512 0.00247 13.6 N/A 10000 170000 N/A 9400

Tomato 5512 0.00414 22.8 N/A 6200 100000 N/A 5800

Broccoli 5512 0.000661 3.65 N/A 39000 650000 N/A 37000

Cauliflower 5512 0.000635 3.5 N/A 41000 670000 N/A 39000

Cabbage 5512 0.000639 3.52 N/A 40000 670000 N/A 38000

Sewer

Cucurbit (Cucumber) 5512 0.000229 1.3

0.0062 0.23 No Data 420000 N/A 2800000 360000 N/A

Cucurbit (Cantaloupe) 5512 0.00027 1.5 350000 N/A 2300000 300000 N/A

Cucurbit (Pumpkin) 5512 0.000107 0.6 890000 N/A 5900000 770000 N/A

Cucurbit (Squash) 5512 0.000172 0.9 560000 N/A 3700000 490000 N/A

Cucurbit (Watermelon) 5512 0.000157 0.9 610000 N/A 4000000 530000 N/A

Pepper 5512 0.00247 13.6 39000 N/A 260000 34000 N/A

Tomato 5512 0.00414 22.8 23000 N/A 150000 20000 N/A

Broccoli 5512 0.000661 3.65 140000 N/A 950000 120000 N/A

Cauliflower 5512 0.000635 3.5 150000 N/A 990000 130000 N/A

Cabbage 5512 0.000639 3.52 150000 N/A 990000 130000 N/APage 19 of 39

Table 5 : Summary of Short

- and Intermediate

- Term Occupational Handler Exposure and Risk Estimates for Paclobutrazol Seed Treatment Uses

Seed Type lbs seed

treated/day a Application

Rate b

(lb ai/lb seed) Amount

Handled per day (lb ai/day) Baseline

Dermal Unit Exposure c (mg/lb ai) Baseline

Inhalation Unit Exposure c (ug/lb ai) PPE

- G

Dermal

Unit Exposure c (mg/lb ai) Baseline

Dermal

MOE d PPE

- G

Dermal

MOE d Baseline

Inhal ation

MOE e Total

Baseline

MOE Total MOE

(Baseline

Inhalation + Gloves)

Bagger

Cucurbit (Cucumber) 5512 0.000229 1.3

0.0091 0.16 No Data 280000 N/A 4000000 260000 N/A

Cucurbit (Cantaloupe) 5512 0.00027 1.5 240000 N/A 3400000 220000 N/A

Cucurbit (Pumpkin) 5512 0.000107 0.6 610000 N/A 8500000 570000 N/A

Cucurbit (Squash) 5512 0.000172 0.9 380000 N/A 5300000 350000 N/A

Cucurbit (Watermelon) 5512 0.000157 0.9 410000 N/A 5800000 380000 N/A

Pepper 5512 0.00247 13.6 26000 N/A 370000 24000 N/A

Tomato 5512 0.00414 22.8 16000 N/A 220000 15000 N/A

Broccoli 5512 0.000661 3.65 98000 N/A 1400000 91000 N/A

Cauliflower 5512 0.000635 3.5 100000 N/A 1400000 93000 N/A Cabbage 5512 0.000639 3.52 100000 N/A 1400000 93000 N/A Multiple Activi ti es Cucurbit (Cucumber) 5512 0.000229 1.3

No Data 1.6 0.042 N/A 62000 400000 N/A 54000

Cucurbit (Cantaloupe) 5512 0.00027 1.5 N/A 52000 340000 N/A 45000

Cucurbit (Pumpkin) 5512 0.000107 0.6 N/A 130000 850000 N/A 110000

Cucurbit (Squash) 5512 0.000172 0.9 N/A 82000 530000 N/A 71000

Cucurbit (Watermelon) 5512 0.000157 0.9 N/A 90000 580000 N/A 78000

Pepper 5512 0.00247 13.6 N/A 5700 37000 N/A 4900

Tomato 5512 0.00414 22.8 N/A 3400 22000 N/A 2900

Broccoli 5512 0.000661 3.65 N/A 21000 140000 N/A 18000

Cauliflower 5512 0.000635 3.5 N/A 22000 140000 N/A 19000 Cabbage 5512 0.000639 3.52 N/A 22000 140000 N/A 19000

a HED default for lb seed treated per day from HED Exposure Science Advisory Council Policy 15.

b Application Rates based on existing labels for paclobutrazol.

c Unit Exposures from HED Exposure Science Advisory Council Policy 14.

d Dermal Dose (mg/kg/day) = dermal unit exposure (mg/ lb ai) x application rate (lb ai/lb seed) x amount treated (lb seed/day) x absorption factor (24.5%) / body weight (8 0 kg adult). Dermal MOE = NOAEL (10.0 mg/kg/day for short

- and intermediate

- term exposure ) / Dermal Dose (mg/kg/day). Level of concern = 100 0

.

e Inhalation Dose (mg/kg/day) = inhalation unit exposure (mg/ lb ai) x application rate (lb ai/lb seed) x amount treated (lb seed/day) x absorption f actor (100%) / body weight (8 0 kg adult). Inhalation MOE = NOAEL (10 .0 mg/kg/day for short

- and intermediate

- term exposure ) / Inhalation Dose (mg/kg/day). Level of concern = 100 0

.Page 20 of 39 Table 6 : Summary of Secondary Handler (Planter) Exposures and Risks for Paclobutrazol

Crop Application

Rate a (lb ai/lb seed) Seeds/lb b seeds planted/acre b lbs

seed/acre Amount

Handled per day c (lb ai/day) PPE

- G Dermal

Unit Exposure (mg/lb ai) d Baseline

Inhalation Unit Exposure (ug/lb ai) d PPE

- G

Dermal

MOE e Baseline

Inhalation

MOE f Total MOE

(Baseline

Inhalation + Gloves)

Cucurbit Seed (Cucumber) 0.000229 12000 139392 11.6 0.21 0.25 3.4 61000 1100000 58000

Cucurbit Seed (Cantaloupe) 0.00027 16000 38848 2.4 0.052 0.25 3.4 250000 4500000 240000

Pepper 0.00247 50000 69696 1.4 0.2 8 0.25 3.4 47000 850000 45000

Cucurbit Seed (Pumpkin) 0.000107 1600 7260 4.5 0.03 9 0.25 3.4 340000 6100000 320000

Cucurbit Seed (Squash) 0.000172 1920 15374 8.0 0.11 0.25 3.4 120000 2100000 110000

Cucurbit Seed (Watermelon) 0.000157 4800 43560 9.1 0.11 0.25 3.4 110000 2100000 100000

Tomato 0.00414 120000 130680 1.1 0.36 0.25 3.4 36000 650000 34000

Broccoli 0.000661 80000 210845 2.6 0.1394 0.25 3.4 94000 1700000 89000

Cauliflower 0.000635 80000 23232 0.3 0.0148 0.25 3.4 890000 16000000 840000

Cabbage 0.000639 45000 98010 2.2 0.1113 0.25 3.4 120000 2100000 110000

a Application Rates based on existing labels for paclobutrazol. b Taken from a Biological and Economic Analysis Division memo entitled, “ Acres Planted per Day and Seeding Rat es of Crops Grown in the United States” ( J. Becker and S. Ratnayake; 3/24/11). c Amount Handled per Day = Application Rate (lb ai/seed) * lbs seed/acre * 80 acres.

d Unit Exposures from HED Exposure Science Advisory Council Policy 14. No data is available for baseline dermal exposure (i.e., no gloves).

e Dermal Dose (mg/kg/day) = dermal unit exposure (mg/ lb ai) x application rate (lb ai/lb seed) x amount treated (lb seed/day) x absorption factor (24.5%) / body weight (8 0 kg adult). Dermal MOE = NOAEL (10.0 mg/kg/day for short

- and intermediate

- term exposure ) / Dermal Dose (mg/kg/day). Level of concern = 100 0

. f Inhalation Dose (mg/kg/day) = inhalation unit exposure (mg/ lb ai) x application rate (lb ai/lb seed) x amount treated (lb seed/day) x absorption factor (100%) / body weight (8 0 kg adult). Inhalation MOE = NOAEL (10 .0 mg/kg/day for short

- and intermediate

- term exposure ) / Inhalation Dose (mg/kg/day). Level of concern = 1000.Page 21 of 39



### 4.2 Occupational Post

- application Exposure and Risk

HED uses the term post

- application to describe exposures that occur when individuals are present in an environment that has been previously treated with a pesticide (also referred to as re

entry exposure). Such exposures may occur when workers e nter previously treated areas to perform job functions, including activities related to crop production, such as scouting for pests or harvesting.

4.2.1 Dermal Post

- Application Risk

In the case of paclobutrazol , there is a potential for post

- appli cati on dermal exposure to workers following foliar applications of paclobutrazol to tu rf, golf courses , and ornamentals in greenhouse and nurseries

. It is the policy of HED to use the best available data to assess post

application exposure. Sources of generic post

- application data, used as surrogate data in the

absence of chemical

- specific data, are derived from Agricultural Reentry Task Force (ARTF) exposure monitoring studies, and, as proprietary data, are subject to the data protection provisions of FIFRA. The standard values recommended for use in predicting post

- application exposure that are used in this assessment, known as “transfer coefficients”, are presented in the “Science Advisory Council for Exposure (ExpoSAC) Policy 3” (http://www.epa.gov /pesticides/science/exposac_policy3.pdf), which, along with additional information about the ARTF data, can be found at http://www.epa.gov/pesticides/science/post

app

- exposure

- data.html

.

Table 7 provides a summary of the transfer coefficients and activities associated with turf and ornamentals in greenhouse and nurseries

.

Table 7 . Post

- application Activities and Dermal Transfer Coefficients.

Use Site Transfer Coefficients (cm 2 /hr) Activities

Turf 3,700 golf course maintenance

Ornamentals in

Greenhouse and

Nurseries 230 transplanting, irrigation (hand watering),
hand harvesting, container moving, hand
weeding, pinching, tying/training,
propagating, hand pruning

1900 irrigation



### In addition, the following assumptions and data were used in the paclobutrazol dermal post

application assessment:

• Application Rate = 0. 75 lb ai/A for turf

• Application Rate = 0. 13 lb ai/A for poinsettas

• Application Rate = 0.59 lb ai/A for chrysanthemums

• Exposure Duration = 8 hours per day

• Body Weight = 80 kg

• Chemical

- specific TTR data submitted in support of the paclobutrazol turf uses (MRID 45214201) . In the study, Turf Enhancer 2SC Plant Growth Regulator was applied t o turfPage 2 2 of 39



### at three test sites located in Madera, California, North Rose, New York, and Creedmoor, North Carolina. Each test site consisted of one untreated control plot (containing 50 subplots) and one treated plot (containing 60 subplots). The first applic ation was made at an application rate of 0.5 lb ai/A and the remaining applications were made at 0.75 lb ai/A. The turf application was made in California with a 60

- gallon tank pressure sprayer. The turf application was made in New York with a 30

- gallon c one shaped tank with a

commercial tractor

- mounted boom. The turf application was made in North Carolina

with a commercial tractor

- mounted sprayer equipped with a 5

- foot boom. The Modified California Roller technique was used to evaluate the amount of tra nsferable residues from turf grass. For the California test site, the average paclobutrazol TTR value was 0.0821 ug/cm 2 

### following the third application. The residues dropped below the level of detection fourteen days after treatment, third application. For the New York test site, the average paclobutrazol TTR value was 0.0212 ug/cm 2 

### following the third application. The residues dropped below the level of detection eight days after treatment three. For the North Carolina test site, the average paclobutr azol TTR value was 0.156 ug/cm 2


### following the fourth application. The residues dropped below the level of detection

twenty

- two days after treatment four. The TTR level used in this assessment (0.077 ug/cm 2 

### ) is based on the California data as it resulted in the highest predicted Day 0

residues

. Appendix A has more specific information regarding the TTR study.

• Chemical

- specific dislodgeable foliar residue ( DFR ) data submitted in support of the paclobutrazol poinsettia uses (MRID 45336601). In the study, BONZI Ornamental Growth Regulator was applied to chrysanth emums in a greenhouse. A single application was made to chrysanthemums in separate greenhouses by a hand

- held boom powered by

CO 2 

### . Leaf discs were collected using a Birkestrand 1.7 84 cm (0.702 inch) diameter leaf punch. The average total paclobutrazol DFR on chrysanthemums was 0.755 ug/cm 2



### twenty

- four hours after the application. By day thirty

- five, the average total paclobutrazol residues declined to 0.202 ug/cm 2 

### . The DFR values did not drop below the limit of quantitation (0.005 ug/cm 2 

### ) during the timeframe of the study. Appendix A has more specific information regarding this DFR study.

• Chemical

- specific D F R data submitted in support of the chrysanthemum uses (MRID 45310801). In this study, Bonzi Ornamental Growth Regulator was applied to poinsettias

in shadehouses . Three applications were made to poinsettias at 7

- day intervals in a commercial shadehouse in Stuart, Florida. The three applications were made at a rate of

0.13 l b ai/Acre with a backpack sprayer with a hand

- held boom powered by CO 2 

### . The field trial consisted of one treated plot and one untreated plot. Leaf discs were collected using a Birkestrand 2.54 cm (1 inch) diameter leaf punch. The average total paclobutr azol DFR value on poinsettias was 0.439 ug/cm 2 

### after the third (final) application. By thirty

- five days after the last application, the total paclobutrazol residue declined to <LOQ (0.005 ug/cm 2 

### ). Appendix A has more specific information regarding

this D FR study.

Daily dermal exposures were calculated on each post

- application day after application using the following equation:

DE (t) 

### (mg/day) = (TR (t) 

### (μg/cm 2 

### ) x TC (cm 2 

### /hr) x Hr/Day)/1000 (μg/mg)Page 23 of 39



### Where:

DE(t) = Daily exposure or amount deposited on the surface of the skin at

time (t) attributable for activity in a previously treated area, also referred to as potential dose (mg ai/day); TR(t) = Transferable residues that can be dislodgeable foliar residue at

time “t” ( μ g/cm 2 

### );

TC = Transfer Coefficien t (cm 2 

### /hour); and Hr/day = Exposure duration meant to represent a typical workday (hours).

A summary of the estimated occupational post

- application r isks are provided in Table 8

. The

short

- and intermediate

- term risk estimates for golf course maintenance activities do not exceed

HED’s level of concern (MOEs ≥ 1000) using predicted Day 0 residue values fr o m the TTR study. The short

- and intermediate

- term risk estimates for ornament als in greenhouses and

nurseries do not exceed HED’s level of concern (MOEs ≥ 1000) using predicted Day 0 residue

values from either the Chrysanthemum or Poinsettia DFR data for all activities except for hand set irrigation. Hand set irrigation would not be performed in greenhouses and thus this issue only applies to nursery situations.

Table 8 : Summary of Short

- and Intermediate

- term Occupational Post

- Application Risks for Paclobutrazol

Crop/Site Activities Transfer

Coefficient (cm 2 /hr) Application

Rate (lb ai/A) Predicted

Day 0 TTR

or DFR (ug/cm 2 ) Day 0 Dermal

Dose (mg/kg/day) d Day 0

MOE e Day X at

which MOE

>= LOC

Turf a golf course

maintenance 3,700 0.75 0.077 0.007 1500 N/A

Ornamentals in

Greenhouse and Nurseries using Chrysanthemum DFR

Data b transplanting,

irrigation, hand harvesting, container moving, hand weeding, pinching, tying/ training, propagating, hand pruning 230 0.59 0.68 0.0041 2,500 N/A

Irrigation (hand set) f 1900 0.59 0.68 0.034 300 40

Ornamentals in

Greenhouse and Nurseries using

Poinsettia DFR Data c transplanting, irrigation, hand harvesting, container moving, hand weeding, pinching, tying/ training, propagating, hand pruning 230 0.59 0.47 0.0027 3800 N/A

Irrigation (hand set) f 1900 0.59 0.47 0.022 460 6

a. TTR data represents CA which was the test site with the highest residues. b. Chrysanthemum DFR data represents use in a greenhouse in Oregon. c. Poinsettia DFR data represents use in a shadehouse in Florida

d. Dermal Dose = [DFR or TTR (ug/cm 2 ) x Tc (cm 2 /hr) x 0.001 mg/ug x 8 hrs/day x DAF (24.5%)] body weight (80 kg) e. Dermal MOE = NOAEL (10 mg/kg/day)/ Dermal Dose (mg/kg/day). f. Hand set irrigation only applies to nursery settings.Page 24 of 39



### Restricted Entry Interval: The REI listed on the existing paclobutrazol labels is based on the acute toxicity of the technical material. Paclobutrazol is classified as Toxicity Category III for the acute oral route, Toxicity Category II for the acute dermal toxicity route, and Toxicity Category III for eye and skin irritation. It is not a skin sensitizer. In accordance with the WPS

, acute Toxicity Category I II and II chemicals require a 12

- or 24

- hour REI, respectively. Based on the acute dermal toxicity, the 12

- hour REI that appears on the current paclobutrazol labels may not be adequate and should be revisited. Special consideration should also be given to use of hand set irrigation in nurseries.

4.2. 2 Occupational Post

- application Inhalation

Based on the Agency's c urrent practices, a quantitative post

- application inhalation exposure assessment was not performed for paclobutrazol at this time primarily because paclobutrazol’s vapor pressure ( 1.28 x 10 - 9 

### mm Hg @ 25.0°C) and Henry's Law Constant (8.09 x 10 - 10 

### atm

m 3 

### /mol) indicate that the compound is relatively non

- volatile under field conditions. However, there are multiple potential sources of post

- application inhalation exposure to individuals performing post

- application activities in previously treated fields. T hese potential sources include volatilization of pesticides and resuspension of dusts and/or particulates that contain pesticides. The Agency sought expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fu ngicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and received the SAP’s final report on March 2, 2010 ( http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html ). The Agency is in the process of evaluating the SAP repor t as well as available post

- application inhalation exposure data generated by the Agricultural Reentry Task Force and may, as appropriate, develop policies and procedures, to identify the need for and, subsequently, the way to incorporate occupational

post

- application inhalation exposure into the Agency's risk assessments. If new policies or procedures are put into place, the Agency may revisit the need for a quantitative occupational

post

- application inhalation ex posure assessment for paclobutrazol

.

5.0 R ESIDENTIAL (NON

- OCCUPATIONAL) EXPOSURE

Paclobutrazol is currently registered for use as a foliar spray for turf (including parks, athletic fields, residential lawns, and golf courses). Although, paclobutrazol products do not appear to be specifically marketed towards residential handler use (i .e., homeowners); a residential handler assessment was performed to be protective of any such use. A residential post

- application assessment was also performed as use of paclobutrazol in parks, residential lawns, and golf courses is expected to result in residential post

- application exposure. In assessing these exposures, the Health Effects Division’s 2012 Standard Operating Procedures for Residential Pesticide Exposure Assessment: Lawns/Turf was used. Some of the data included in the

Lawns/Turf SOP are proprietary and thus are subject to the data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).Page 25 of 39



### 5.1 Residential Handler Exposure and Risk

Assessing exposures and risks resulting from residential uses is very similar to assessing occupational exposures and risks, except that residential handler exposure scenarios do not use a tiered approach for personal protection using increasing levels of PPE in residential handler risk

assessments. Homeowner handler assess ments are based on the assumption that individuals are wearing shorts, short

- sleeved shirts, socks, and shoes, and homeowner handlers are expected to complete all tasks associated with the use of a pesticide product including mixing/loading if

needed as we ll as the application. Residential handler exposure scenarios are considered to be

short

- term only, due to the infrequent use patterns associated with homeowner products.

It has been determined that exposure to pesticide handlers is likely during the res idential use of paclobutrazol on lawns. The quantitative exposure/risk assessment developed for residential handlers is based on the following scenarios:

Mixing/Loading/Applying Liquid s with Manually

- Pressurized H andwand; Mixing/Loading/Applying Liquid s with Hose End Sprayer; Mixing/Loading/Applying Liquid s with Backpack Sprayer; Loading/Applying Granules with Push Type Spreader; and Loading/Applying Granules with Belly Grinder

It is the policy of HED to use the best available data to assess handler exposure. Sources of generic handler data, used as surrogate data in the absence of chemical

- specific data, include the Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1), the Outdoor Residential Exposure Task Force (ORETF) database, or other reg istrant

- submitted occupational exposure studies. Some of these data are proprietary (e.g., ORETF data), and subject to the data protection provisions of FIFRA. The standard values recommended for use in predicting residential handler exposure that are us ed in this assessment, known as “unit exposures”, are outlined in the 2012

Lawns/Turf SOP.

Handler dermal and/or inhalation exposures are estimated by multiplying the application

method

- specific unit exposure by an estimate of the amount of active ingredient handled in a day, using the following algorithm:

where:

E = exposure (mg/day);

UE = unit exposure (mg/lb ai);

AR = application rate (e.g., lb ai/ft 2 

### , lb ai/gal); and

A = area treated or amount handled (e.g., ft 2 

### /day, gal /day).

Dermal and/or inhalation doses are estimated using the following algorithm:Page 26 of 39



### where:

D = dose rate (mg/kg

- day);

AF = absorption factor (dermal and/or inhalation); and

BW = body weight (kg).

Dermal and inhalation risks were combined in this assessment, since the toxicological effects for these exposure routes were similar. Dermal and inhalation risks were combined using the following formula:

Total MOE = Point of Departure (mg/kg/day) / Combined derma l + inhalation dose (mg/kg/day)

Short

- term risks for residential handlers are presented in Table 9 . Intermediate

- term exposures are not likely because of the intermittent nature of applications by homeowners. Short

- term combined dermal plus inhalation r isk estimates to residential handlers do not exceed HED’s level

of concern for all scenarios (i.e., MOEs ≥ 100 0 ) except for belly grinder application (MOE=790)

.

Table 9

. Residential Handler Baseline Dermal and Inhalation Exposures

Crop Grouping Application

Rate a Area

Treated Daily b Dermal

Unit Exposure (mg/lb ai) Inhalation

Unit Exposure

(mg/lb ai) Baseline Baseline Inhalation Total

(lb ai/A) (acres/day) Baseline Baseline Dermal

Dose c (mg/kg/day) Dermal

MOE d Dose e

(mg/kg/day) MOE f Baseline

Dermal +

Baseline

Inhalation

MOE g

Mixer/Loader/Applicator (Liquids)

- Manually Pressurized Handwand Application

Turf 0.75 0.023 h 63 0.018 0.0033 3000 0.0000039 2600000 3000

Mixer/Loader/Applicator (Liquids)

- Hose End Sprayer Application

Turf 0.75 0.5 13.4 0.022 0.024 2500 0.000048 1200000 2500

Mixer/Loader/Applicator (Liquids)

- Backpack Sprayer Application

Turf 0.75 0.023 h 130 0.14 0.0069 1500 0.00003 330000 1400

Mixer/Loader/Applicator (Granules)

- Push Type Spreader Application

Turf 0.5 0.5 0.81 0.0026 0.00062 16000 0.0000081 1200000 16000

Mixer/Loader/Applicator (Granules)

- Belly Grinder Application

Turf 0.5 0.023 h 360 0.039 0.013 790 0.0000056 1800000 790

a. Application rates based on existing labels.

b. Based on HED’s Standard Operating Procedures for Residential Exposure Assessment; Lawns/Turf (January 2012).

c. Dermal Dose (mg/kg/day) = daily unit exposure (mg/ lb ai) x application rate (lb ai/acre or lb ai /gal) x acres or gal treated x 24. 5% derm al absorption / bod y weight (8 0 kg).

d. Inhalation Dose (mg/kg/day) daily unit exposure (μg/ lb ai) x application rate (lb ai/acre or lb ai/gal) x acres or gal treated x 100%

inhalati on absorption / body weight (8 0 kg).

e. Dermal MOE = NOAEL (1 0 mg/kg/day) / dermal daily dose (mg/ kg/ day). Level of concern = 100 0

. f. Inhalation MOE = NOAEL ( 1 0 mg/kg/day) / inhalation daily dose (mg/ kg/ day). Level of concern = 100 0

. g. Combined De rmal + Inhalation MOE = NOAEL (1 0 mg/kg/day) / Combined dermal + inhalation dose (mg/ kg/day).

h. 0.023 acres is equivalent to 1,000 ft 2Page 27 of 39



### 5.2 Residential Post

- Application Exposure/Risk

Paclobutrazol can be used in many areas that can be frequented by the general population including residential areas (e.g., home lawns). As a result, individuals can be exposed by entering these areas if they have been previously treated.

5.2.1 Post

- application Inhalation

Based on the Agency's current practices, a quantitative residential post

- application inhalation exposure assessment was not performe d for paclobutrazol at this time primarily because paclobutrazol’s vapor pressure ( 1.28 x 10 - 9 

### mm Hg @ 25.0°C) and Henry's Law Constant (8.09 x

10 - 10 

### atm m 3 

### /mol) indicate that the compound is relatively non

- volatile under field conditions. The Agency soug ht expert advice and input on issues related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) in December 2009. The Agency received the SAP’s final report on March 2, 2010 ( http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html ). The Agency is in the process of evaluating the SAP report and may, as appropriate, developing policies and procedures, to identifying the need for and, subsequently, the way to incorporat e post

- application inhalation exposure into the Agency's risk assessments. If new policies or procedures are put into place, the Agency may revisit the need for a quantitative post

- application inhalation exposure assessment for paclobutrazol

.

5.2 .2 Residential Post

- Application Dermal and Incidental Oral

Short

- term dermal and incidental oral exposure and risk estimates have been assessed for paclobutrazol. Dermal and oral exposures were not combined as the toxicological effects from

the dermal and oral routes of exposure are different

. . The scenarios, routes of exposure and lifestages assessed include:

Physical activities on turf: adults (dermal) and children 1 < 2 years old (dermal and incidental oral); Mowing: adults (dermal) and children 11 < 16 years old (dermal); and Golfing: adults (dermal), children 11 < 16 years old (dermal), and children 6 < 11 years old (dermal).

The lifestages (i.e., adults,children 1<2 years old, children 11 < 16 years old, and children 6 < 11 years old) selected for each post

- application scenario are based on an analysis provided as an Appendix in the 2012 Residential SOPs. These lifestages are not the only lifestages that could be potentially exposed for these post

- application scenarios; however, the assessment of these lifestages is health protective for the exposures and risks for any other potentially exposed lifestages.

The following equations and assumptions were used to calculate post

- application risk estimates:

Dermal exposure:Page 28 of 39 

### E = TTRt * CF1 * TC * ET

where :
E = exposure (mg/day);

TTRt = turf transferable residue on day "t" (μg/cm 2 

### );

CF1 = weight unit conversion factor (0.001 mg/μg);

TC = transfer coefficient (cm 2 

### /hr); and

ET = exposure time (hr/day).

Assumptions:

A TTR study was used to assess the liquid formulation scenarios ( Turf Enhancer® 2SC Plant Growth Regulator Transferable Turf Residue Study

– MRID No.: 45214201). Data were collected at three sites in the TTR study including New York, California, and North

Carolina. Data from the Calif ornia site was used in this assessment as it resulted in the highest predicted Day 0 residues (see Section 4.2.1 and Appendix A for more details)

. Transfer coefficients:

o Physical activities on turf: 180,000 cm 2 

### /hr for adults and 49,000 cm 2 

### /hr for

children 1 < 2 years old for liquids and 200,000 cm 2 

### /hr for adults and 54,000

cm 2 

### /hr for children for granulars

o Mowing: 5,500 cm 2 

### /hr for adults and 4,500 cm 2 

### /hr for children 11 < 16 years old

o Golfing: 5,300 cm 2 

### /hr for adults, 4,400 cm 2 

### /hr for children 11 < 16 ye ars old, and
2,900 cm 2 

### /hr for children 6 < 11 years old Exposure time (hr):

o Physical activities on turf: 1.5 hr for adults and children

o Mowing: 1 hr

o Golfing: 4 hr

Hand

- to

- Mouth :

E = [HR * ( F M 

### * SA H 

### ) * (ET * N_Replen) * (1

- (1

- SE ) (Freq_Replen/N

- Replen) 

### )]

where:

E = exposure (mg/day);

HR = hand residue loading (mg/cm 2 

### );

F M 

### = fraction hand surface area mouthed / event (fraction/event);

SA H 

### = typical surface area of one hand (cm 2 

### );

ET = exposure time (hr/day); N_Replen = number of replenishment intervals per hour (intervals/hour);

SE = saliva extraction factor (i.e., mouthing removal efficiency); and Freq_Replen = number of hand

- to

- mouth contacts events per hour (events/hour).

andPage 29 of 39



### where:

HR = hand residue loading (mg/cm 2 

### );

Fai hands 

### = fraction ai on hands compared to total surface residue from dermal

transfer coefficient study (unitless);

DE = dermal exposure (mg); and

SA H 

### = typical surface area of one hand (cm 2 

### ).

Object

- to

- Mouth :

E = [OR* CF1 * SAM O 

### * (ET * N_Replen) * (1

- (1

- SE O 

### ) (Freq_Replen/N_Replen) 

### )]

where:

E = exposure (mg/day);

OR = chemical residue loading on the object on day “t” (ug/cm 2 

### );

CF1 = weight unit conversion factor (0.001 mg/μg);

SAM O 

### = area of the object surface that is mouthed (cm 2 

### /event);

ET = exposure time (hr/day); N_Replen = number of replenishment intervals per hour (intervals/hour);

SE = saliva extraction factor (i.e., mouthing removal efficiency); and Freq_Replen = number of object

- to

- mouth contact event s per hour (events/hour).

and

OR = AR * F O 

### * CF2 * CF3

where:

OR = chemical residue loading on the object (μg/cm 2 

### );

AR = application rate (lbs ai/ft 2 

### or lb ai/acre);

F O 

### = fraction of residue available on the object (unitless);

CF2 = weight unit conve rsion factor (4.54 x 10 8 

### μg/lb); and

CF3 = area unit conversion factor (1.08 x 10 - 3 

### ft 2 

### /cm 2 

### or 2.47 x 10 - 8



### acre/cm 2 

### ). Soil Ingestion :

E = SRt * SIgR * CF1

where:

E = exposure (mg/day);

SRt = soil residue on day "t" (μg/g); SIgR = ingestion rate of soil (mg/day); and

CF1 = weight unit conversion factor (1 x 10 - 6 

### g/μg).

and

SRt = AR * FS * (1

- F D 

### ) t 

### * CF2 * CF3 * CF4Page 30 of 39



### where:

SRt = soil residue on day "t" (μg/g);

AR = application rate (lbs ai/ft 2 

### or lb ai/acre);

FS = fraction of ai available in uppermost cm of soil (fraction/cm);

F D 

### = fraction of residue that dissipates daily (unitless);

t = post

- application day on which exposure is being assessed;

CF2 = weight unit conversion factor (4.54 x 10 8 

### μg/lb);

CF3 = area unit conversion factor (1.08 x 1 0 - 3 

### ft 2 

### /cm 2 

### or 2.47 x 10 - 8 

### acre/cm 2 

### ); and

CF4 = soil volume to weight unit conversion factor (0.67 cm 3 

### /g soil). Mowing :

E = TTRt * CF1 * TC * ET

where :
E = exposure (mg/day);

TTRt = turf transferable residue on day "t" (μg/cm 2 

### );

CF1 = weight unit conversion factor (0.001 mg/μg);

TC = transfer coefficient (cm 2 

### /hr); and

ET = exposure time (hr/day).

and

TTRt = AR * F * (1

- F D 

### ) t 

### * CF2 * CF3

where : TTRt = turf transferable residue on day "t" (μg/cm 2 

### );

AR = application rate (lbs ai/ft 2 

### or lb ai/acre);

F = fraction of ai retained on turf (unitless);

F D 

### = fraction of residue that dissipates daily (unitless);

t = post

- application day on which exposure is being assessed;

CF2 = weight unit conversion factor (4.54 x 10 8 

### μg/lb); and

CF3 = area unit conversion factor (1.08 x 10 - 3 

### ft 2 

### /cm 2 

### or 2.47 x 10 - 8 

### acre/cm 2 

### ).

Golfing :

E = TTRt * CF1 * TC * ET

where :
E = exposure (mg/day);

TTRt = turf transferable residue on day "t" (μg/cm 2 

### );

CF1 = weight unit conversion factor (0.001 mg/μg);

TC = transfer coefficient (cm 2 

### /hr); and

ET = exposure time (hr/day).

andPage 31 of 39 

### TTRt = AR * F * (1

- F D 

### ) t 

### * CF2 * CF3

where : TTRt = turf transferable residue on day "t" (μg/cm 2 

### );

AR = application rate (lbs ai/ft 2 

### or lb ai/acre);

F = fraction of ai retained on turf (unitless)’

F D 

### = fraction of residue that dissipates daily (unitless);

t = post

- application day on which exposure is being assessed;

CF2 = weight unit conversion factor (4.54 x 10 8 

### μg/lb); and

CF3 = area unit conversion factor (1.08 x 10 - 3 

### ft 2 

### /cm 2 

### or 2.47 x 10 - 8 

### acre/cm 2 

### ).

For each scenario, absorbed dose (normalized to body weight) was calculated as:

where :
D = dose (mg/kg

- day);

E = exposure (mg/day);

AF = absorption factor (dermal only; 24.5 %); and

BW = body weight (79.5 kg for adults; 56.8 kg for children 11 < 16 years old, 31.8 kg for children 6 < 11 years old, 11.4 kg for children 1 < 2 years old).

Dermal and incidental oral risk estimates were calculated using the following formula:

MOE = Point of Departure (mg/kg/day) / Dermal or incidental oral dose (mg/kg/day)

where : Dermal NOAEL = 10 mg/kg/day, and

Incidental oral NOAEL = 18.8 mg/kg/day

A summary of the adult and children short

- term dermal exposure and risk estimates is shown in

Tab le 10

. All adult and children mowing and golf dermal risk estimates for both liquid and granular formulations do not exceed HED’s level of concern (MOEs ≥ 1000). All adult and children playing on treated turf dermal risk estimates for both liquid and gra nular formulations

exceed HED’s level of concern (MOEs < 1000).

Table 10

. Short

- Term Dermal Residential Post

- application Exposure and Risk Estimates for Paclobutrazol

Lifestage Post

- application Exposure Scenario Application Rate a
(lb ai/A) TTR

(ug/cm2) Dermal Dose b

(mg/kg/day) Dermal

MOEs c
Liquid Formulations

Adult

Dermal Physical Activities on Turf

0.75 0.077 d 0.064 160 Mowing 0.0013 7700 Golfing 0.005 2000

Child 11 < 16 years old Mowing 0.0015 6700 Golfing 0.0058 1700 Child 6 < 11 years old Golfing 0.0069 1500Page 32 of 39

Table 10

. Short

- Term Dermal Residential Post

- application Exposure and Risk Estimates for Paclobutrazol

Lifestage Post

- application Exposure Scenario Application Rate a
(lb ai/A) TTR

(ug/cm2) Dermal Dose b

(mg/kg/day) Dermal

MOEs c
Child 1 < 2 year old Physical Activities on Turf 0.12 82

Granular Formulations

Adult

Dermal Physical Activities on Turf

0.5 0.011 e 0.010 970 Mowing 0.00019 53000 Golfing 0.00073 14000

Child 11 < 16 years old Mowing 0.00022 46000 Golfing 0.00084 12000 Child 6 < 11 years old Golfing 0.00099 10000 Child 1 < 2 year old Physical Activities on Turf 0.019 520 a. Application rates = maximum application rates from labels.

b. Dermal Dose (mg/kg/day) = TTR (μg/cm 2 ) x 0.001 (mg/μg) x short

- term TC (cm 2 /hr) x ET (hr/day) x DAF (40%) BW (kg)

c. Dermal MOE = NOAEL (10 mg/kg/day) / Dermal Dose (mg/kg/day) d. Representative of California TTR data taken from MRID No.: 45214201 ; the site t hat resulted in the highest TTR values.

e. Turf Transferable Resid ues (TTR) = Application Rate x 0.2 % x 11.2



### A summary of the children short

- term oral non

- dietary ingestion exposure and risk estimates is

shown in Table 11. All children oral non

- dietary ingestion risk estimates for both liquid and granular formulations do not exceed HED’s level of concern (MOEs ≥ 1000).

Table 11. Short

- Term Oral Non

- dietary Injestion Residential Post

- application Exposure and Risk Estimate s for Paclobutrazol

Lifestage Post

- application Exposure Scenario Application Rate a (lb ai/A) TTR

(ug/cm2) Oral Dose b, c, d

(mg/kg/day) Oral

MOEs e
Liquids

Child 1 < 2 year old Oral Hand

- to

- Mouth

0.75 0.077 f 0.010 1800 Object

- to

- Mouth 0.00032 59000 Soil Ingestion 0.000025 770000

Granulars

Child 1 < 2 year old Oral Hand

- to

- Mouth

0.5 0.011 g 0.00074 25000 Object

- to

- Mouth 0.00023 82000 Soil Ingestion 0.000016 1200000 Episodic Granular Ingestion N/A h

a. Application rates = maximum application rates from labels.

b. Hand

- to

- Mouth Dose (mg/kg/day) = E = [HR * ( F M * SA H ) * (ET * N_Replen) * (1

- (1

- SE ) (Freq_Replen/N

- Replen) )] c. Object

- to

- Mouth Dose (mg/kg/day) = E = [OR* CF1 * SAM O * (ET * N_Replen) * (1

- (1

- SE O ) (Freq_Replen/N_Replen) )]

d. Soil Ingestion Dose (mg/kg/day) = E = SRt * SIgR * CF1

e. Oral MOE = NOAEL (1 8.8 mg/kg/day) / Oral Dose (mg/kg/day) f. Representative of California TTR data taken from MRID No.: 45214201 ; the site that resulted in the highest TTR values.

h. Turf Transferable Resid ues (TTR) = Application Rate x 0.2 % x 11.2 g. No endpoints identified from the available developments toxicity studies (rat and rabbit) appropriate for an acute dietar y assessment for paclobutrazol and thus no asses sment is required for episodic granular ingestion.



### 5.3 Combined Exposure

HED combines risk values resulting from separate exposure pathways when it is likely they can occur simultaneously based on the use pattern, the behavior associated with the exposed population, and the hazard associated with the points of departure. HED reviewed all residential sources of exposure to determine which residential exposure scenarios would be appropriate to combine with dietary exposure for an aggregate risk assessment.

HED did not combine exposure resulting from adult handler and post

- application exposurePage 33 of 39



### resulting from treated lawns and/or golfing because of the conservative assumptions and inputs within each estimated exposure scenario. HED believes that combing exposures resulting from

handler and post

- application activities would result in an overestimate of adult exposure. Therefore, HED selected the most conservative adult residential scenario, dermal post

application exposure (MOE = 160) as the contributing source of residential exposure to be combined with the dietary exposure for the agg regate assessment.

The children’s oral exposure is based on post

- application hand

- to

- mouth exposures only (MOE= 1800) . To include exposure from object

- to

- mouth and soil ingestion in addition to hand

- to

mouth could result in a very conservative estimation of exposure, as it would overestimate the potential for oral exposure. Furthermore, although there is the potential for co

- occurrence of dermal and oral exposure, the toxicological effects from the dermal and oral routes of exposure

are different. As a result, a combined residential exposure assessment is not possible for children. Therefore, two independent children’s aggregate assessments are required (post

application dermal combined with dietary exposure and post

- application oral combined with

dieta ry exposure) to ensure no unacceptable risk will result to children when combining residential and dietary exposure for purposes of estimating an aggregate risk.

Table 12 summarizes the residential exposure scenarios that are to be used for estimating

agg regate exposure.

Table 1 2 . Combined Residential Exposure and Risk Estimates for Paclobutrazol

Use Site Handler

Dermal a Handler

Inhalation a Post

- application

Dermal MOE b Hand

- to

- Mouth

MOE c

Dose MOE Dose MOE Dose MOE Dose MOE

Adults

– Turf (Granulars) 0.013 790 0.0000056 1800000 0.010 970 N / A

Adults

– Turf (Liquids) 0.0069 1500 0.00003 330000 0.064 160 N / A

Children 1 < 2 Years Old

- Turf (Granulars) N / A N / A 0.019 520 0.00 0 74 25000

Children 1 < 2 Years Old

- Turf (Liquids) N / A N / A 0.12 82 0.0 10 1800

a. See Table 9 : Residential Handler Dermal Exposure and Risk ( granulars represents belly grinder and liquids represents backpack sprayer )

b. See Table 10 : Dermal Po st

- application Exposure and Risk

c. See Table 11 : Hand

- To

- Mouth Exposure and Risk



### 5.4 Spray Drift

Off

- target movement of pesticides can occur via many types of pathways and it is governed by a variety of factors. Sprays that are released and do not deposit in the application area end up off

target and can lead to exposures to those it may directly contact. They can also deposit on surfaces where contact with residues can eventually lead to indirect exposures ( e.g. , children playing on lawns where residues have deposited next to treated fields). The potential risk

estimates f

rom these residues can be calculated using drift modeling coupled with methods employed for residential risk assessments for turf products.

The approach to be used for quantitatively incorporating spray drift into risk assessment is basedPage 34 of 39



### on a premise of compliant applications which, by definition, should not result in direct exposures to individuals because of existing label language and other regulatory requirements intended to prevent them. 1 

### Direct exposures would include inhalation of the spray plume or being sprayed directly. Rather, the exposures addressed here are thought to occur indirectly through contact with impacted areas, such as residential lawns, when compliant applications are conducted. Given this premise, exposures for children (1 to 2 years old) and adults who have contact with turf where residues are assumed to have deposited via spray drift thus resulting in an indirect exposure are the focus of this analysis analogous to how exposures to turf products are

considered in risk assessmen t.

Paclobutrazol is not registered on use sites that are likely to result in spray drift outside of the currently registered turf uses. Since p ost

- application exposure from the direct turf applications is already assessed for paclobutrazol (see above in Section 5.2), quantitative assessment of spray drift is not required for paclobutrazol at this time.

1 

### This approach is consistent with the requirements of the EPA’s Worker Protection Standard which, when included on all labels, precludes direct exposure pathways.Page 35 of 39 

### Appendix A: Paclobutrazol DFR and TTR Study ResultsPage 36 of 39



### Summary of the TTR Study: Determination of Transferable Residues of Paclobutrazol
Turf Treated with Turf Enhancer 2SC Plant Growth Regulator (MRID 45214201)

The study was designed to determine the total tranferable residues (TTR) of paclobutrazol dislodged from turf treated with Turf Enhancer 2SC Plant Growth Regulator, a liquid soluble concentrate formulation containing 22.3% paclobutrazol as the active ingre dient. The test site consisted of three fields located in Madera, California, North Rose, New York, and Creedmoor, North Carolina. Each test site consisted of one untreated control plot (containing 50 subplots) and one treated plot (containing 60 subplots ). The first application was made at an application rate of 0.5 lb ai/A and the remaining applications were made at 0.75 lb ai/A. Applications were made in California (60

- gallon tank pressure sprayer was used) and New York (30

- gallon cone shaped tank was used) with a commercial tractor

- mounted boom and in North Carolina with a

commercial tractor

- mounted sprayer equipped with a 5

- foot boom. The Modified California Roller technique was used to evaluate the amount of transferable residues from turf grass.

First

- order dissipation kinetics were assumed to generate dissipation curves for paclobutrazol at all three test sites. The individual residue data was collected after the last application through the first day when all triplicate TTR levels were less tha n the level of quantitation (LOQ). For values that were less than the LOQ, a value was used that is one

- half of the LOQ. A linear regression analysis was conducted using the natural logarithm of the individual TTR values from

cloth dosimeters.

For the California test site, the average paclobutrazol TTR value was 0.0821 ug/cm 2 

### following the third application. The residues dropped below the level of detection fourteen days after

tre atment, third application

. For the New York test site, the average paclo butrazol TTR value was 0.0212 ug/cm 2 

### following the third application. The residues dropped below the level of detection eight days after treatment three. For the North Carolina test site, the average paclobutrazol TTR value was 0.156 ug/cm 2 

### following the fourth application. The residues dropped below the level of detection twenty

- two days after treatment four.

The overall average low and high level field fortification recoveries for California were >90%. The overall average low and high level field fortification recoveries for New York and North Carolina were both <90%. The raw field residue samples were corrected using the corresponding average low or high fortification level recovery for each test site when the

recoveries were <90%. For New York, the field residue samples that had the average low level field fortification were corrected for an 83.7% low level average recovery. All of the field samples from the North Carolina test site were corrected for either the average low level

r ecovery of 81.5% or the average high level recovery of 83.5%.

Based on the results, the half

- life was determined to be 1.77 days (R 2 

### =0.916) for California, 1.50 days (R 2 

### =0.983) for New York and 2.56 days (R 2 

### =0.815) for North Carolina.

The results of th e study are acceptable for risk assessment purposes.Page 37 of 39

Table A1 . Summary of TTR Values and Regression Analysis Results for Turf Enhancer 2SC Plant Growth

Regulator Transferable Turf Residue Study (MRID# 45214201).

Input/Parameter New York California North Carolina

Application Rate (lb ai/A) 0.51 (1st application)

0.76 (2nd application)

0.77 (3rd application) 0.51 (1st application)

0.76 (2nd application)

0.77 (3rd application) 0.51 (1st application)

0.75 (2nd application)

0.76 (3rd application)

0.75 (4th application)

Spray Volume (GPA) † 44.0 (1 st application)

44.4 (2 nd application)

44.9 (3 rd application) 44.4 (all applications) 44.0 (1 st , 2 nd , & 3 rd
application) 43.6 (4 th application)

Measured Average Day 0 Residue (μg/cm 2 ) 0.212 (1st application) 0.0821 (1st application) 0.0373 (1st application)

Predicted Day 0 Residue (μg/cm 2 ) ‡ 0.018 0.077 0.050

Slope

- 0.4616

- 0.39084

- 0.2703

Half

- life (days) 1.50 1.77 2.56

R 2 0.983 0.916 0.815Page 38 of 39



### Summary of the DFR Study for Treated Chrysanthemums with Bonzi Ornamental Growth Regulator (MRID# 45310801)

The study review was designed to determine the dissipation of dislodgeable foliar residues (DFR) of paclobutrazol from chrysanthemums treated with BONZI Ornamental Growth

R egulator, a liquid formulation containing 0.4% paclobutrazol as the active ingredient (ai). The test site consisted of commercial greenhouses located in Aurora, Oregon. The field trial consisted of one treated plot and one untreated plot that were locate d in separate greenhouses. A single application was made to chrysanthemums by a hand

- held boom powered by CO 2 

### . The application was made at an application rate of 0.56 lb ai/A. Leaf discs were collected using a Birkestrand 1.784 cm (0.702 inch) diameter leaf punch.

The DFR samples were collected prior to and immediately after the application, and on days 1, 2, 4, 7, 10, 14, 21, 28, and 35 after the application. The average total paclobutrazol DFR on chrysanthemums was 0.755 ug/cm 2 

### twenty

- four hours afte r the application. By day thirty

- five, the average total paclobutrazol residues declined to 0.202 ug/cm 2 

### . The DFR values did not drop below the limit of quantitation (0.005 ug/cm 2 

### ) during the timeframe of the study.

The DFR values were not corrected bec ause the average low level field fortification recovery was >90%. The midpoint was used between the two fortification concentrations (1.25 ug/cm 2 

### ) as the break point and all of the DFR values were below the midpoint.

Based on the results, the half

- life was determined to be 22.7 days (R 2 

### =0.774). The study was found to be acceptable for use in exposure and risk assessments.

Table A2

. Summary of DFR Values and Regression Analysis Results for Treated Chrysanthemums with Bonzi (MRID# 45310801).

Input/Parameter Oregon

Application Rate (lb ai/A) 0.56 lb ai/A bench space

Spray Volume (GPA) † 2.87 qt/100 sq ft of bench space (1 st application)

Measured Average Day 0 Residue (μg/cm 2 ) 0.467 (1st application) 0.755(2 nd application) 0.623(3 rd application) Predicted Day 0 Residue (μg/cm 2 ) ‡ 0.684 Slope

- 0.03053

Half

- life (days) 22.7

R 2 0.774Page 39 of 39



### Summary of the DFR Study for Treated Poinsettas with Bonzi Ornamental Growth Regulator (MRID# 45336601)

The study was designed to determine the dissipation o f dislodgeable foliar residues of paclobutrazol applied to poinsettia s with Bonzi Ornamental Growth R egulator, a liquid formulation containing 0.4 % paclobutrazol as the active ingredient (ai). Three applications were made to poinsettias at 7

- day intervals in a commercial shadehouse in Stuart, Florida. The three applications were made at a rate of 0.13 lb ai/Acre with a backpack sprayer with a hand

- held boom powered by CO 2 

### . The field trial consisted of one treated plot and one untreated plot. Leaf discs were collected using a Birkestrand 2.54 cm (1 inch) diameter leaf punch.

The DFR samples were collected prior to and following each application, and on days 1, 2, 4, 7, 10, 14, 21, 28, and 35 following the last application. The average total paclobutrazol DFR value on poinsettias was 0.439 ug/cm 2 

### after the third (final) application. By thirty

- five days after the last application, the total paclobutrazol residue declined to <LOQ (0.005 ug/cm 2 

### ).

The DFR values were corrected using the av erage percent recovery of the field fortification samples (88%). The midpoint between the two fortification concentrations (1.25 ug/cm 2 

### ) was used as the break point.

The DFR residue values were not corrected that were below the LOQ (0.005 ug/cm 2 

### ). For residue values that were less than the level of quantification (LOQ) (0.005 ug/cm 2 

### ), 1⁄2 LOQ was

used in the calculations.

Based on the results, the half

- life was determined to be 4.55 days (R2=0.911).

The study was found to be acceptable for use in exposure and risk assessments.

Table A3 . Summary of DFR Values and Regression Analysis Results for Treated Poinsettias with Bonzi (MRID# 45336601).

Input/Parameter Florida

Application Rate (lb ai/A) 0.13 (all application s )

Spray Volume (GPA) † 2.9 qt/100 sq ft of bench space (1 st application ) 3.0 qt/100 sq ft of bench space (2 nd application) 3.0 qt/100 sq ft of bench space (3 rd application)

Measured Average Day 0 Residue (μg/cm 2 ) 0.292 (1st application ) 0.326(2 nd application) 0.439 (3 rd application) Predicted Day 0 Residue (μg/cm 2 ) ‡ 0.471 Slope

- 0. 1522

Half

- life (days) 4.55

R 2 0. 914