Page 1 of 28 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION



### MEMORANDUM

DATE: October 12 , 2011

SUBJECT: Trinexapac

- Ethyl : Occupational and Residential Exposure/Risk Assessment for

Proposed Uses on grasses grown for seed, sugarcane, and cereals (wheat, barley, and oats)

.

PC Code: 1 12602 DP Barcode: D 392798

Decision No.: Registration No. : Petition No.: NA Regulatory Action: Section 3 New Use Risk Assessment Type: NA Case No.:

T XR No.: NA CAS No.:

MRID No.: NA 40 CFR:

FROM: Monica Hawkins, Ph.D., M.P.H., Environmental Health Scientist

Risk Assessment Branch 6 Health Effects Division (7509P)

THROUGH: Charles Smith, Senior Environmental Scientist

Risk Assessment Branch 6 Health Effects Division (7509P)

TO: Sheila Piper

, Senior Chemist/Risk Assessor

Bethany Benbow, Biologist

Herbicide Branch Registration Division (7505P)Page 2 of 28



### INTRODUCTION

The registrant, Syngenta Crop Protection Incorporated has submitted a Section 3 registration application for proposed new uses of the active ingredient (ai) trinexapac

- ethyl on cereals, sugarcane, and grasses grown for seed production. This memorandum contains an occupational and residential exposure and risk as sessment for the requested use. An analysis of the occupational and residential exposures and risks from all currently registered uses of trinexapac

ethyl is also included since significant changes were made to the trinexapac

- ethyl hazard

assessment since the last trinexapac

- ethyl assessment was completed by the Health Effects Division (HED) (Kelly Schumacher, DP 356118, 9/5/08).

HED has examined the occupational and residential exposure (ORE) databases for trinexapac

ethyl . Based on the attached ORE a ssessment

, HED has determined that there no risks that exceed HED’s level of concern (MOEs ≥ 100). Prior to the Registration Division ( RD ) granting the requested use s , HED recommends that:

1) The proper REIs are put in place on the labels to reflect the acute toxicity of trinexapac

- ethyl ( Toxicity Category III for acute dermal, oral, and primary eye irritation, and Category IV for acute inhalation and primary skin irritation). Per the Worker Protection Standard (WPS), a 12

- hr restricted entry interval (R EI) is required for chemicals classified under Toxicity Category III/IV. The Registration Division (RD) should ensure the proper REIs are put in place on the labels to reflect these requirements

.

Note: This memorandum was reviewed by the Exposure Scien ce Advisory Council (ExpoSAC)

on 08 / 4 /2011.Page 3 of 28 

### Table of Contents

1.0 EXECUTIVE SUMMARY

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

2.0 HAZARD PROFILE

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

3.0 USE PROFILE

................................ ................................ ................................ .......................... 8

4.0 OCCUPATIONAL EXPOSURE

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

4.1 Occupational Handler Exposure and Risk

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

4.2 Occupational Post

- application Exposure and Risk

................................ ........................... 19 5.0 RESIDENTIAL (NON

- OCCUPATIONAL) EXPOSURE

................................ ....................... 22 5.1 Residential (Non

- Occupational) Handler Exposure and Risk

................................ ................ 23

5.2 Residential Post

- Application Exposure and Risk

................................ ................................ .. 24 5.3 Spray Drift

................................ ................................ ................................ ................................ 27Page 4 of 28



### 1.0 EXECUTIVE SUMMARY

Use Profile

Trinexapac

– ethyl, is a cyclohexadione plant growth regulator that is marketed as an emulsifiable concentrate, wettable powder packed in water

- soluble bags, granules, and as a technical chemical used for formulation only

. A Section 3 registration is being requested by Syngenta Crop Protection, Incorporated, for t rinexapac

- ethyl for use on wheat, barley, oats

, and sugar cane and to amend the use on grass grown for seed production at a rate of 0.5 lb ai/A. The maximum single application rate proposed for wheat, barley, and oats is 0.11 lb ai/A and for sugarcane is

0.31 lb ai/A. The end

- use products are Palisade EC (EPA Reg. No. 100

- 949, emulsifiable concentrate and Palisade 2EC (EPA Reg. No. 100

- 1241, emulsifiable concentrate)

. Trinexapac

ethyl is also registered for use on turf areas such as sod farms, golf courses, sports fields, and

cemeteries and similar are as. The label

- required personal protective equipment (PPE) for occupational applicators is a long

- sleeved shirt, long pants, shoes, and socks.

Hazard Profile

The Trinexapac

- ethyl risk assessment team evaluated the toxicology database and toxicity endpoi nt and point of departure selections for risk assessment. Quantification of dermal and inhalation risks were performed using a developmental toxicity rabbit study. The LOAEL (Lowest Observed Adverse Effect Level) from this study was 360 mg/kg/day based o n a decrease in the mean number of fetuses/litter and an increase in post

- implantation loss. The NOAEL (No Observed Adverse Effect Level) from this study was 60 mg/kg/day. A target MOE of 100 is considered adequate for adults and children (10X for inters pecies extrapolation, 10X for intraspecies variability, and a 1X for LOAEL to NOAEL extrapolation ). Based on a dermal absorption study in male rats, absorption of Trinexapac

- ethyl was determined to be 77.5% at 10 hours. The female body weight of 60 kilog rams (kg) was used in the short

- term dermal and inhalation assessment because the dose and endpoint were selected from a developmental study in which fetal effects were observed (a decrease in the mean number of fetuses/litter and an increase in post

- impla ntation loss). The use of the 60 kg body weight is protective of all workers, including males and females.

An endpoint of concern for the incidental oral scenario (hand to mouth behavior in children 1

- 6 years) is not available from the trinexapac

- ethyl toxicity studies.

Since the effects seen in the developmental rabbit study (selected for the short

- term/intermediate

term assessment) and the chronic oral dog toxicity study (selected for the short

term/intermediate

- term assessment) are the same, these routes of exposure should be combined.

Trinexapac

- ethyl is classified as “Not likely to be carcinogenic to humans.” This is based on the lack of carcinogenic potential noted in the available studies. There is no concern for

mu tagenicity and clastogenici ty.

Occupational Exposure/RiskPage 5 of 28



### It is anticipated that there will be occupational handler and post

- application exposure from the proposed agricultural uses as well as all of the currently registered uses of trinexapac

- ethyl

.

Occupational Handler

No chemical specific data were available to assess potential exposure to pesticide handlers. The estimates of exposure to pesticide handlers are based upon surrogate study data available in the Pesticide Handlers Exposure Database (PHED) Version 1.1 and t he Agricultural Handler Exposure Task Force (AHETF). 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 i ntermediate

- term (1 to 6 months).

L ong

- term exposures (greater than 6 months) are not anticipated based on the proposed use
pattern. 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. A Margin of Exposure (MOE) greater than or equal to 100 for dermal and inhalation

routes is deemed adequate to protect occupational trinexapac

- ethyl handlers. All handler scenarios resulted in MOEs greater than the level of concern LOC (i.e., MOEs ≥ 100) when wearing labeled personal protective equipment (PPE) (e.g

. , long

- sleeve shirt, long pants, shoes, socks, chemical

- resistant gloves, and protective eyewear) and, therefore are not of concern.

Occupational Post

- application

Occupational short

- and intermediate

- term dermal exposures are expected from post

- application

activities. Chemical

- specific data relevant to post

- application exposure ( i.e

. , dislodgeable foliar residue [DFR] data) were not submitted; therefore, post

- application exposure estimates were calculated using standard HED Exposure SAC assumptions (body weight and exposure duration)

and transfer coefficients (SOP # 3.2 ). Using default DFR value s, risks are not a concern for any
post

- application occupational scenario on day 0, except for hand

- harvesting sugarcane where

risks are of concern until 8 days after application (short

- term and intermediate

- term post

application)

.

Restri cted Entry Interval: C urrent trinexapac

- ethyl labels have either no REI, 0 days, or a 4

hour REI. The trinexapac

- ethyl technical material has been classified in Toxicity Category III for acute dermal, oral, and primary eye irritation, and Category IV for acute inhalation and primary skin irritation. Per the Worker Protection Standard (WPS), a 12

- hr restricted entry interval (REI) is required for chemicals classified under Toxicity Category III/IV. The

R egistration D ivision (RD) should ensure the proper REIs are put in place on the labels to

reflect these requirements

.

Based on HED’s occupational postapplication exposure assessment, REIs for hand

- harvesting sugarcane were estimat ed to be 8 days for short

- term and intermediate

- te rm exposure

. However,

HED does not recommend that sugarcane REI’s be changed on the trinexapac

- ethyl labels at this time based on two main issues. One, almost all sugarcane harvesting in the United States is done mechanically. Two, the proposed trinexap ac

- ethyl labels have a 28

- day pre

- harvest interval (PHI) for sugarcane so hand harvesting should not occur until after 28 days which is protectivePage 6 of 28



### of the estimated REIs

.

Residential Exposure/Risk

HED determined that there is a potential for residential exposure to trinexapac

- ethyl from the currently registered turf uses . HED assumes that only short

- term exposures are applicable to

residential risk assessments. Intermediate

- term and chronic exposu res were not assessed for residential handler and post

- application risk assessments

.

Residential Handler

No chemical

- specific handler exposure data were submitted in support of this registration. It is the policy of the HED to use data from the PHED V ersion 1.1. In addition, data from the Outdoor Residential Exposure Task Force ( ORETF ) is used, as appropriate. The combined dermal plus inhalation risks to residential handlers do not exceed HED’s level of concern for all scenarios (i.e., MOEs ≥ 100)

.

Residential Post

- application

HED determined that there is a potential for exposure from entering trinexapac

- ethyl

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

application exposures to adults and children.

Short

- term dermal risks we re assessed for adults and children (3 to < 6 year olds)

. The residential post

- appl ication MOEs ranged from 450 to 24 ,000 and therefore do not exceed HED’s level of concern (MOE ≥ 100).

Review of Human Research

This exposure/risk assessment relies i n part on data from studies in which adult human subjects were intentionally exposed to a pesticide or other chemical. Many such studies, involving exposure to many different pesticides, comprise generic pesticide exposure databases such as the PHED, the AHETF , and the Agricultural Reentry Task Force ( ARTF ) Database. EPA has

reviewed all the studies in these multi

- pesticide generic exposure databases, and on the basis of available evidence has found them to have been neither fundamentally unethical nor significantly deficient relative to standards of ethical research conduct prevailing when they were conducted. There is no regulatory barrier to continued reliance on these studies, and all applicable requirements of EPA’s Rule for the Protection of Human Subjects of Research (40 CFR Part 26)

have been satisfied.

2.0 HAZARD PROFILE

The acute toxicity for trinexapac

- ethyl technical formulation was classified as Toxicity Categor y III for acute oral, dermal, and eye irritation, and IV for acute inhalation and skin irritation (Table 1).

Table 1. Acute Toxicity Profile

- Trinexapac

- ethyl (97%)Page 7 of 28

Guideline

No. Study Type MRID Results Toxicity Category

870.1100 Acute oral [rat]

41563901 ♂ LD 50 = 4613 mg/kg ♀ LD 50 = 4212 mg/kg

Combined LD 50 = 4458 mg/kg III

870.1200 Acute dermal [rabbit] 41563910 LD 50 > 4000 mg/kg III

870.1300 Acute inhalation [rat] 41563912 LC 50 ≥ 5.3 mg/L IV

870.2400 Acute eye irritation [rabbit] 41563914 Minimal irritant; cleared by 72 hours III

870.2500 Acute dermal irritation [rabbit] 41563916 Slightly irritating; cleared by day 7 IV

870.2600 Skin sensitization [guinea pig] 41869522 Not a dermal sensitizer N/A



### Short

- term and inhalation risks are based on systemic effects (decrease in the mean number of fetus/litter and an increase in post

- implantation los s) observed at the LOAEL of 360 mg/kg/day in the developmental toxicit y rabbit study. The NOAEL from this study was 60 mg/kg/day. A target MOE of 100 is considered adequate for adults and children (10X for interspecies extrapolation, 10X for intraspecies variability, and a 1X for LOAEL to NOAEL extrapolation ). Based on a dermal absorption study in male rats, absorption of Trinexapac

- ethyl was 77 .5% at 10 hours. The female body weight of 60 kg was used in the short

- term dermal and inhalation assessment because the dose and endpoint were selected from a developmental study in which fetal effects were observed (a decrease in the mean number of fetu ses/litter and an increase in
post

- implantation loss). The use of the 60 kg body weight is protective of all workers, including

males and females.

An endpoint of concern for the incidental oral scenario is not available from the available trinexapac

- et hyl toxicity studies. The rationale for this conclusion is based on the following weight of evidence considerations: 1) the toxicity observed during the appropriate duration of concern (short/intermediate term) were observed only at high doses [LOAEL = 90 0 mg/kg/day in the dog, 1000 mg/kg/day in the rat, and 1212 mg/kg/day in the reproduction study]; 2) the brain lesions observed in the chronic dog study are not appropriate for this scenario since the brai n lesions were seen only at termination (i.e. after exposure to 1

- year) and toxicity observed after chronic exposure is not appropriate for application to the short/intermediate term scenarios; 3) the brain lesion observed in the chronic study are not expected to occur after short term exposure due to the lack of similar lesions or associated toxicity (i.e., clinical neurologic signs)

in the 90

- day studies in rats or dogs; 4) the cause for concern for the brain lesions is low because of the minimal lesion severity, lack of associated changes (i.e., gliosi s, myelin loss astrocyte hypertrophy, neuronal necrosis etc), and the non

- specific nature of the lesions (i.e., focal vacuoles); 5) the overall toxicity profile of this chemical clearly shows that toxicity is observed only at high doses (lowest LOAEL = 36 0 m/k/d in the chronic dog study); and 6) the in utero endpoint identified in the rabbit study is not appropriate for this population of concern (children).

Since the effects seen in the developmental rabbit study (selected for the short

- term/intermediate

term assessment) and the chronic ` oral dog toxicity study (selected for the short

term/intermediate

- term assessment) are the same, these routes of exposure s hould be combined.

Trinexapac

- ethyl is classified as “Not likely to be carcinogenic to humans.” This is based on the lack of carcinogenic potential noted in the available studies. There is no concern for mutagenicity and clastogenicity.Page 8 of 28



### Table 2 pre sents the selected points of departure for Trinexapac

- ethyl.

Table 2. Summary of Toxicological Doses and Endpoints for Trinexapac

- ethyl for use in Occupational
Human Health Risk Assessments

. Exposure/
Scenario Point of

Departure Uncertainty/

FQPA Safety

Factors RfD, PAD,

Level of
Concern for
Risk
Assessment Study and Toxicological Effects

Acute Dietary (General Population, including

Infants and Children) No appropriate endpoint for the general population including infants and children

Acute Dietary (Females 13

- 49 years of age) NOAEL = 60

mg/kg UF A 

### = 10x

UF H 

### = 10x FQPA SF= 1x Acute RfD = 0.6

mg/kg

aPAD = 0.6 mg/kg Developmental rabbit study

MRID 41869524

LOAEL = 360 mg/kg, based on a

decrease in mean number of

fetuses/litter and an increase in post

implantation loss

Chronic Dietary (All Populations) NOAEL= 31.6

mg/kg/day UF A 

### = 10x

UF H 

### = 10x FQPA SF= 1x Chronic RfD =

0.32 mg/kg/day

cPAD = 0.32 mg/kg/day C

hronic oral toxicity study

– dog

MRID 42779402/ 42779401

LOAEL = 357 mg/kg/day, based on
elevated serum cholesterol values in females, mucoid feces in females and bloody feces in both sexes, and minimal, focal vacuolation of the dorsal medial hippocampus and/or

lateral midbrain in both sexes Cancer (oral, dermal, inhalation) Classification: “Not likely to be Carcinogenic to Humans”

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 ri sk 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 in sensitivity among members of the human population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose.Page 9 of 28



### Table 2. Summary of Toxicological Doses a nd Endpoints for Trinexapac

- ethyl for use in Occupational

Human Health Risk Assessments

. Exposure/
Scenario Point of

Departure Uncertainty/

FQPA Safety

Factors RfD, PAD,

Level of
Concern for
Risk

Assessment Study and Toxicological Effects

Incidental
Oral (Short and

Intermediate

Term ) N o appropriate endpoint was available for the incidental oral scenario.

Dermal &
Inhalation

Short and

Intermediate

Term (all populations) (1

- 6 months) NOAEL= 60

mg/kg/day

Dermal absorption rate
= 77.5% of oral absorption

Inhalation absorption rate

= 100% of oral absorption UF A 

### = 10x

UF H 

### = 10x FQPA SF= 1x Residential LOC

for MOE = 100

Occupational
LOC for MOE =

100 Developmental rabbit study

MRID 41869524

LOAEL = 360 mg/kg, based on a

decrease in mean number of fetuses/litter and an increase in post

implantation loss

Cancer (oral, dermal, inhalation) Classification: “Not likely to be Carcinogenic to Humans”

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 =

uncertaint y factor. UF A = extrapolation from animal to human (interspecies). UF H = potential variation in sensitivity among members of the human population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). Rf D = reference dose. MOE = margin of exposure. LOC = level

of concern.



### 3.0 USE PROFILE

Trinexapac

- ethyl is a cyclohexadione plant growth regulator that is marketed as an emulsifiable concentrate, wettable powder packed in water

- soluble bags, granules, and as a technical chemical used for formulation only. A Section 3 registration is being requested by Syngenta Crop Protection, Incorporated for Trinexapac

- ethyl for use on wheat, barley, oats, and sugar cane and to amend the use on grasses grown for seed production at a rate of 0.5 lb ai/A. The maximum application rate proposed for wheat, barley, and oats is 0.11 /b ai/A and sugarcane is 0.31 lb ai/A. The use pattern for the proposed new uses of Palisade 2EC (trinexapac

- ethyl 25.5%, emulsifiable concentrate) and Palisade EC (trinexapac

- ethyl 12%, emulsifiable concentrate) , is summarized in

Table 3. Trinexapac

- et hyl is also registered for use on turf areas such as sod farms, golf courses, sports fields, and cemeteries and similar areas

.

The personal protective equipment (PPE) requirements proposed on the Palisade 2EC

and Palisade EC labels , that is consistent with current registrations

, are:Page 10 of 28



### o Applicators and other handlers must wear: long

- sleeved shirt and long pants, chemical

resistant gloves, shoes plus socks, and protective eyewear.

Table 3

. Proposed Use Patterns and Formulations

Product Formulation Use Sites Application

Rates Application

Equipment Max App

Rate per

crop season REI

Palisade

2EC (EPA Reg.

No. 100

- 1241) Emulsifiable

Concentrate Grasses

grown for
seed 0.04

– 0.5

lb ai/A Aerial, ground,

handheld, and chemigation 0.5 lb ai/A

4 hours Cereals 0.04

– 0.11

lb ai/A 0.11 lb ai/A

Sugarcane 0.07

– 0.31

lb ai/A 0.31 lb ai/A

Palisade EC (EPA Reg.

No. 100

- 949) Emulsifiable

Concentrate Grasses

grown for

seed 0.05

– 0.5 lb

ai/A Aerial, ground,

and chemigation 0.5 lb ai/A

0 days Cereals 0.05

– 0.11

lb ai/A 0.11 lb ai/A

Sugarcane 0.06

– 0.31 0.31 lb ai/A



### 4.0 OCCUPATIONAL EXPOSURE

4.1 Occupational Handler Exposure and Risk

HED uses the term “handlers” to describe those individuals who are involved in the pesticide application process. HED believes that there are distinct job functions or tasks related to applications and that exposures can vary depending on the specifics of each task. Job requirements (e.g., amount of chemical to be used in an application), the kinds of equipment used, the target being treated, and the level of protection used by a handler can cause exposure levels to differ in a manner specific to each app lication event. The first step in the handler risk assessment process is to identify the kinds of individuals that are likely to be exposed to Trinexapac

- ethyl during the application process. In order to do this in a consistent manner, HED has developed a series of general descriptions for tasks that are associated with pesticide applications.

Exposure Scenarios

Based upon the proposed trinexapac

- ethyl use patterns, HED assessed risks to occupational pesticide handlers in the following scenarios:

Mix ing/loading liquids for aerial applications Mixing/loading liquids for groundboom applications Mixing/loading liquids for chemigationPage 11 of 28



### Mixing/loading liquids for LCO handgun applications Mixing/loading wettable powders in water soluble bags for aerial appli cations Mixing/loading wettable powders in water soluble bags for chemigation Mixing/loading wettable powders in water soluble bags for groundboom applications Mixing/loading wettable powders in water soluble bags for LCO handgun applications Mixing/loadin g granules for aerial applications Mixing/loading granules for tractor drawn spreader applications Applying sprays for aerial applications Applying sprays for groundboom equipment Applying granules for tractor drawn spreader applications Flagging (liquids) during aerial applications Flagging (granules) during aerial applications Mixing /loading/applying wettable powders for low pressure handwand applications Mixing/loading/applying liquids for backpack sprayer applications Mixing/loading/applying liquids for handgun sprayer applications Mixing/loading/applying liquids for low pressure handwand applications Mixing/loading/applying wettable powders in water soluble bags for backpack sprayer applications Mixing/loading/applying water soluble bags for handgun spr ayer applications Mixing/loading/applying granules for belly grinder applications Mixing/loading/applying granules for push type spreader applications

Area or the Amount Treated

The daily areas treated were defined for each handler scenario (in appropriate units) by determining the amount that can be reasonably treated in a single day. When possible, the assumptions for daily areas treated are taken f rom HED ExpoSAC Policy #9: “Standard Values for Daily Acres Treated in Agriculture ”, which was r evised on July 5, 2000. Values used for area treated in each scenario include: 350 acres for application with fixed

- wing aircraft, flagging, and chemigation; 80 acres for groundboom application (40 acres for groundboom application for golf courses), 100 a cres for mixing/loading for multiple LCO handgun application s , 80 acres for tractor drawn spreader application (40 acres for golf courses), 0.023 (1,000 ft 2 

### ) acres for low pressure handwand application, backpack sprayer application, and belly grinder appli cation; and 5 acres for handgun sprayer application.

Personal Protective Equipment

Occupational handler exposure assessments are completed by HED using different levels of personal protection. HED typically evaluates all exposures with a tiered approach . The lowest tier is represented by the baseline exposure scenario (i.e., long

- sleeve d shirt, long pants, shoes, and socks) followed by increasing the levels of personal protective equipment or PPE (e.g., gloves, double

- layer body protection, and respirat ors) and engineering controls (e.g., enclosed cabs and closed mixing/loading systems). This approach is always used by HED in order to be able to define label language using a risk

- based approach. In addition, the minimal level of adequate protection for a chemical is generally considered by HED to be the most practicalPage 12 of 28



### option for risk reduction (i.e., over

- burdensome risk mitigation measures are not considered a practical alternative).

Unit E xposures

No chemical

- specific handler exposure data were subm itted in support of this Section 3 registration. To assess handler exposures for regulatory actions when chemical

- specific monitoring data are not available, HED relies on the most scientifically

- reliable surrogate data currently available from various so urces such as the Pesticide Handler Exposure Database (PHED), the Agricultural Handler Exposure Task Force (AHETF), and the Outdoor Residential Exposure Task Force (ORETF). Some of this data, such as the industry task force data, is compensatory, subject to the data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act ( FIFRA ) . HED policy on use of surrogate data is described in more detail on the Agency's website (http://www.epa.gov/pesticides/science/handler

- exposure

- data.html ).

Scenario

- specific surrogate exposure data, including their sources, are presented in the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (http://www.epa.gov/pesticides/science/handler

- exposure

- table.pdf).

There are three basic risk mitigation approaches considered appropriate for controlling occupational exposures. These include administrative controls, the use of personal protective equipment or PPE, and the use of engineering controls. Occupational handler exposure

ass essments are often completed by HED using baseline, PPE, and engineering controls. [Note: Administrative controls available generally involve altering application rates for handler exposure scenarios. These are typically not utilized for completing handle r exposure assessments.] The baseline clothing level scenario for occupational exposure scenarios is generally an individual wearing long pants, a long

- sleeved shirt, no chemical resistant gloves, and no respirator. The first level of mitigation generally applied is PPE. PPE may involve the use of an additional layer of clothing, chemical

- resistant gloves, and a respirator. The next level of mitigation considered in the risk assessment process is the use of appropriate engineering controls which, by desi gn, attempt to eliminate the possibility of human exposure. Examples of commonly used engineering controls include enclosed tractor cabs and cockpits, closed mixing/loading/transfer systems, and water

- soluble packets.

Typically, HED completes short

- and intermediate

- term assessments for occupational scenarios

in all cases b ecause both durations are likely and acceptable use/usage data are not available to justify deleting intermediate

- term scenarios. Based on use data and label instructions, HED

believes that occupational exposures for trinexapac

- ethyl may occur over a single day or up to weeks at a time for many use

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

t erm exposures are not expected; therefore, a long

- term assessment was not conducted.

Equations and Calculations:

Daily Exposure : Daily dermal and inhalation handler exposures are estimated for each applicable handler task with the application rate, the area treated or amount handled in a day, andPage 13 of 28



### the applicable unit exposure using the following formula:

Daily Exposure (mg ai/day) = Unit Exposu re (mg ai/lb ai handled) x Application Rate (lbs ai/area) x Daily Area Treated (area/day)

Where:

Daily Exposure = Amount (mg ai/day) inhaled that is available for inhalation absorption; Unit Exposure = Unit exposure value (mg ai/lb ai) derived from August 1998 PHED data; Application Rate = Normalized application rate based on a logical unit treatment, such as acres; and Daily Area Treated = Normalized application area based on a logical unit treatment such as acres (A/day).



### Daily Dose: D aily dermal and inhalation dose is calculated by normalizing the daily exposure by body weight and adjusting, if necessary, with an appropriate dermal or inhalation absorption factor using the following formula:

Average Daily Dose (mg/kg/day) = Daily Exposure (mg ai/day) x (Absorption Factor (%/100)) / Body Weight (kg)

Where:

Average Daily Dose = Absorbed dose received from exposure to a pesticide in a given scenario (mg ai/kg body weight/day); Daily Exposure = Amount (mg ai/day) inhaled that is available for inhalation absorption; 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 in 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 handler s 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 Adverse Effec t 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 inhalation risks were combined using the following equation:

Total MOE = 1/ ((1/ Dermal MOE) + (1/Inhalation MOE))Page 14 of 28



### Short

- term and intermediate

- term risk estimates for occupational handlers are included in Table

4 . All handler scenarios resulted in MOEs greater than th e LOC (MOEs ≥ 100) for dermal, inhalation, and combined dermal and inhalation exposures when wearing labeled PPE (long

sleeve shirt, long pants, shoes, socks, chemical

- resistant gloves, and protective eyewear) and,

therefore are not of concern.

The handle r exposure estimates in this assessment are based on a central tendency estimate of unit exposure and an upper

- percentile assumption for the application rate, and are assumed to be representative of high

- end exposures. The uncertainties associated with th is assessment stem from the use of surrogate exposure data (e.g., differences in use scenario and data confidence), and assumptions regarding that amount of chemical handled. The estimated exposures are believed to be reasonable high

- end estimates based o n observations from field studies and professional judgement.Page 15 of 28



### Table 4. Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposur e (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Mixer/Loader (Liquids)

- Aerial Application

Grasses Grown for Seed 100 0.0376 0.000219 0.5 350 0.085 710 0.00064 94000 700

Sod 100 0.0376 0.000219 0.34 350 0.058 1000 0.00043 140000 1000

Sugarcane 100 0.0376 0.000219 0.31 350 0.053 1100 0.0004 150000 1100

Cereals 100 0.0376 0.000219 0.11 350 0.019 3200 0.00014 430000 3200

Mixer/Loader (Liquids)

- Groundboom Application

Grasses Grown for Seed 100 0.0376 0.000219 0.5 80 0.019 3100 0.00015 410000 3100

Sod 100 0.0376 0.000219 0.34 80 0.013 4500 0.000099 600000 4500

Sugarcane 100 0.0376 0.000219 0.31 80 0.012 5000 0.000091 660000 4900

Golf Course 100 0.0376 0.000219 0.17 40 0.0033 18000 0.000025 2400000 18000

Cereals 100 0.0376 0.000219 0.11 80 0.0043 14000 0.000032 1900000 14000

Mixer/Loader (Liquids)

- Chemigation

Grasses Grown for Seed 100 0.0376 0.000219 0.5 350 0.085 710 0.00064 94000 700

Sod 100 0.0376 0.000219 0.34 350 0.058 1000 0.00043 140000 1000

Sugarcane 100 0.0376 0.000219 0.31 350 0.053 1100 0.0004 150000 1100

Cereals 100 0.0376 0.000219 0.11 350 0.019 3200 0.00014 430000 3200

Mixer/Loader (Liquids)

- LCO Handgun Application

Turf 100 0.0376 0.000219 0.34 100 0.017 3600 0.00012 480000 3600

Mixer/Loader(Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Aerial Application

Sod 100 0.0098 0.00024 0.34 350 0.015 4000 0.00048 130000 600

Mixer/Loader (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Chemigation

Sod 100 0.0098 0.00024 0.34 350 0.015 4000 0.00048 130000 600

Mixer/Loader (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Groundboom Application

Sod 100 0.0098 0.00024 0.34 80 0.0034 17000 0.00011 550000 2600

Golf Course 100 0.0098 0.00024 0.17 40 0.00086 70000 0.000027 2200000 10000Page 16 of 28



### Table 4. Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposur e (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Mixer/Loader (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- LCO Handgun Application

Turf 100 0.0098 0.00024 0.34 100 0.0043 14000 0.00014 440000 2100

Mixer/Loader (Granules)

- Aerial Application

Sod 100 0.0069 0.0017 0.44 350 0.014 4400 0.0044 14000 3300

Mixer/Loader (Granules )

- Tractor Drawn Spreader Applications

Sod 100 0.0069 0.0017 0.44 80 0.0031 19000 0.001 60000 15000

Golf Course 100 0.0069 0.0017 0.17 40 0.00061 99000 0.00019 310000 75000

Applicator (Sprays)

- Aerial

Grasses Grown for Seed 100



### -- -- 0.5 350

-- -- -- 

### -- --

Sod 100



### -- -- 0.34 350

-- -- -- 

### -- --

Sugarcane 100



### -- -- 0.31 350

-- -- -- 

### -- --

Cereals 100



### -- -- 0.11 350

-- -- -- 

### -- --

Applicator (Sprays)

- Groundboom Equipment

Grasses Grown for Seed 100 0.0161 0.00034 0.5 80 0.0083 7200 0.00023 260000 7000

Sod 100 0.0161 0.00034 0.34 80 0.0057 11000 0.00015 390000 10000

Sugarcane 100 0.0161 0.00034 0.31 80 0.0052 12000 0.00014 430000 11000

Golf Course 100 0.0161 0.00034 0.17 40 0.0014 42000 0.000039 1600000 41000

Cereals 100 0.0161 0.00034 0.11 80 0.0018 33000 0.00005 1200000 32000

Applicator (Granules)

- Tractor Drawn Spreader Applications

Sod 100 0.0072 0.0012 0.44 80 0.0033 18000 0.0007 85000 15000

Golf Course 100 0.0072 0.0012 0.17 40 0.00063 95000 0.00014 440000 78000

Flagger (Liquids)

- Aerial Spray Application

Grasses Grown for Seed 100

-- 0.00035 0.5 350

-- -- 0.001 59000

--

Sod 100



### -- 0.00035 0.34 350

-- -- 0.00069 86000 --

Sugarcane 100

-- 0.00035 0.31 350

-- -- 0.00063 95000

--

Cereals 100

-- 0.00035 0.11 350

-- -- 0.00022 270000

--Page 17 of 28



### Table 4. Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposur e (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Flagger (Granules)

- Aerial Application

Sod 100

-- 0.00015 0.44 350

-- -- 0.00039 160000

-- Mixer/Loader/Applicator (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Low Pressure Handwand Application

Edging/Banding 100

-- -- 0.68 0.023

-- -- -- -- --

Turf 100

-- -- 0.34 0.023

-- -- -- -- --

Golf Course 100

-- -- 0.17 0.023

-- -- -- -- --
Mixer/Loader/Applicator (Liquids)

- Backpack Sprayer Application

Edging/Banding 100 2.5 0.03 0.68 0.023 0.00051 120000 0.0000078 7700000 120000

Turf 100 2.5 0.03 0.34 0.023 0.00025 240000 0.0000039 15000000 230000

Golf Course 100 2.5 0.03 0.17 0.023 0.00013 480000 0.000002 31000000 470000

Mixer/Loader/Applicator (Liquids)

- Handgun Sprayer Application

Turf 100 0.45 0.0015 0.34 5 0.0099 6100 0.000043 1400000 6000

Golf Course 100 0.45 0.0015 0.17 5 0.0049 12000 0.000021 2800000 12000

Mixer/Loader/Applicator (Liquids)

- Low Pressure Handwand Applications

Edging/Banding 100 0.33 0.0027 0.68 0.023 0.000067 900000 0.0000007 85000000 890000

Turf 100 0.33 0.0027 0.34 0.023 0.000033 1800000 0.00000035 170000000 1800000

Golf Course 100 0.33 0.0027 0.17 0.023 0.000017 3600000 0.00000018 340000000 3600000

Mixer/Loader/Applicator (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Backpack Sprayer Application

Edging/Banding 100

-- -- 0.68 0.023

-- -- -- -- --

Turf 100

-- -- 0.34 0.023

-- -- -- -- --

Golf Course 100

-- -- 0.17 0.023

-- -- -- -- -- Mixer/Loader/Applicator (Wettable Powders in Water Soluble Bags) (Engineering Controls)

- Handgun Sprayer Application

Turf 100

-- -- 0.34 5

-- -- -- -- --

Golf Course 100

-- -- 0.17 5

-- -- -- -- -- Mixer/Loader/Applicator (Granules)

- Belly Grinder Application

Edging/Banding 100 9.3 0.062 0.88 0.023 0.0024 25000 0.000021 2900000 24000Page 18 of 28



### Table 4. Short

- Term and Intermediate

- Term Occupational Handler Dermal and Inhalation Exposures

Crop Grouping Target MOE Dermal Unit Exposure (mg/lb ai) Inhalation Unit

Exposur e (mg/lb ai) Application

Rate a Area Treated

Daily b PPE

- G Baseline Inhalation Total

PPE

- G Baseline (lb ai/A) (acres/day) Dermal Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f MOE g

Turf 100 9.3 0.062 0.44 0.023 0.0012 49000 0.00001 5700000 49000

Golf Course 100 9.3 0.062 0.17 0.023 0.00047 130000 0.000004 15000000 130000

Mixer/Loader/Applicator (Granules)

- Push Type Spreader Application

Turf 100 0.22 0.0073 0.44 0.5 0.0063 9600 0.00027 220000 9200

Golf Course 100 0.22 0.0073 0.17 0.5 0.0024 25000 0.0001 580000 24000 a. Application Rates based on proposed labels.

b. Science Advisory Council Policy No. 9.1

c . Dermal Dose (mg/kg/day) = daily unit exposure (mg/ lb ai) x dermal absorption ( 7 5 .5 %) application rate (lb ai/acre or lb ai/gal) x acres or gallons treated / body weight (60 kg).

d . Dermal MOE = NOAEL ( 6 0 mg/kg/day) / dermal daily dose (mg/ kg/ day). Level of concern = 100.

e . Inhalation Dose (mg/kg/day) daily unit exposure (μg/ lb ai) x application rate (lb ai/acre or lb ai/gal) x acres treated or gallons treated / body weight (60 kg).

f . Inhalation MOE = NOAEL ( 6 0 mg/kg/day) / inhalation daily dose (mg/ kg/ day). Level of concern = 100.

g . Combined Dermal + Inhalation MOE = NOAEL ( 6 0 mg/kg/day) / Combined dermal + inhalation dose (mg/kg/day)

-- = Data Not Available or Liquid s Exposure Scenario is considered protective of this scenarioPage 19 of 28



### 4.2 Occupational Post

- application Exposure and Risk

In the case of trinexpac

- ethyl , there is a potential for postapplication dermal exposure to field workers following foliar applications o f trinexpac

- ethyl to agricultural crops

. Chemical and

crop

- specific data relevant to post

- application exposure (i.e., dislodgeable foliar residue (DFR) data) for the new trinexpac

- ethyl proposed uses were not submitted. T herefore, dermal exposures during postapplication activities were estimated using dermal transfer coefficients from the Science Advisory Council for Exposure Policy Number 3 (http://www.epa.gov/pesticides/science/exposac_policy3.pdf). This policy reflects adoption of all Agricultural Reentry Exposure Task Force (ARTF) data. Use of the data in this policy requires compensation to the ARTF under FIFRA.

In the absence of chemical

- specific DFR data, HED assumes that 20% of the initial application is

avail able for transfer on day 0 ( i.e., 12 hours after application) and that the residue dissipate s at a
rate of 10% per day. Furthermore, HED also assumes an 8 hour workday for post

- application

workers . Average d aily doses (ADD) were calculated on each post

- a pplication day after application using the following equation s :

Equations/Calculations:

Daily Dermal Exposure : Daily dermal exposures were calculated on each post

- application day after application using the following equation (see equation D2

- 20 from Series 875

- Occupational and Residential Test Guidelines: Group B

- Post

- application Exposure Monitoring
Test Guidelines and Residential SOP 3.2: Post

- application Dermal Potential Doses from

Pesticide Residues on Gardens ):

DE (t) (mg/day) = (DFR (t) (μg/cm 2 ) x TC (cm

2 /hr) x DA x Hr/Day)/1000 (μg/mg)

Where: DE(t) = Daily exposure or amount deposited on the surface of the skin at time (t) attributable attributable for activity in a previously treated area, also referred to as potential dose (mg ai/day);

D FR(t) = Transferable residues that ca n either be dislodgeable foliar or turf transferable

re sidue at time “t” (μg/cm 2 );

TC = Transfer Coefficient (cm 2 /hour);

DA = Dermal Absorption (%); and Hr/day = Exposure duration meant to represent a typical wo rkday (8 hours).

Default DFR (μg/cm 2 ) = AR (lb ai/A) x F x (1

- D) t x CF1 x CF2

Where:

AR = Maximum application rate

F = Fraction of ai retained on the foliage (unitless)

D = Fraction of residue that dissipates daily (unitless)

t = Post

- application day

CF1 = 4.54E+8 μg/lb

CF2 = 2.47E

- 8 A/cm 2



### Daily Dermal Dose: D aily dermal dose is calculated by normalizing the daily exposure by body weight and adjusting, if necessary, with an appropriate dermal absorption factor using thePage 20 of 28



### following formula:

Daily Dermal Dose (mg/kg/day) = Daily Exposure (mg ai/day) x (Absorption Factor (%/100)) / Body Weight (kg)

Where:

Daily Dermal Dose = Absorbed dose received from exposure to a pesticide in a given scenario (mg ai/kg body weight/day ); Daily Exposure = Amount (mg ai/day) inhaled that is available for inhalation absorption; 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 in a risk assessment (kg).



### Margin of Exposure (MOE): The daily dermal dose rec eived by occupational postapplication

workers are compared to the appropriate point of departure (i.e., N OAEL) to assess postapplication risk s. All MOE values are calculated for dermal exposure lev els using the following equation :

MOE = NOAEL (mg/kg/day) / Daily Dermal 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),

DDD = Daily dermal dose is the absorbed dose received from exposure to pesticide (mg/kg/day)

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



### A summary of the estimated occupational post

- application risks as calculated per default DFR

da ta are provided in Table 5 . The post

- application MOEs at day 0 range from 47 to 12,000. The results indicate that occupational post

- application risks, as calculated per HED default values, do not exceed HED’s level of concern (an MOE ≥ 100) on day zero after application for all post

application tasks that were assessed except for hand

- harvesting sugarcane where the MOE increases to 110 within 8 days of application (short

- term and intermediate

- term post

- application)

.Page 21 of 28 Table 5

. Summary of Trinexapac

- ethyl Occupational Short

- Term and Intermediate

- Term Post

application Risks Using Default Data

Crop Grouping Crop Exposure
Potential Max

Foliar

Rate (lb ai/ acre) Transfer
Coefficient (cm 2 /hr) Activities MOE

at Day
Zero Day Acceptable
MOE

Field/Row Crop (Low) Turf/Sod

(Golf Course) Low 0.17 3700 Maintenance 410

--

Field Row Crop (Low) Turf/Sod

(Sod) Low 0.34 0 Roll Harvesting

-- --

670 0 Maintenance,

Slab Harvesting, Transplanting

/ Planting 110

--

Field/Row Crop (Low/Medium) Sugarcane Low

0.31 0 Transplanting

-- --

70 Hand

Weeding 12000

--

High 0 Mechanical Harvesting,

Mechanical Weeding -- --

1100 Scouting 760

17600 Hand

Harvesting 47 8

Field/Row Crop (Low/Medium) Grasses

grown for

seed Low 0.5 0 Mechanical Harvesting, Fertilizing, Irrigation (non

- hand set) -- --

1100 Scouting 470

--

1900 Irrigation

(hand set) 270

--

Field/Row Crop (Low/Medium) Cereals Low 0.11 0 Irrigation (non

- hand set),

Mechanical Harvesting -- --

1100 Scouting 2100

--



### Occupational Post

- application Inhalation

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

- application inhalation exposure

assessment was not performed for trinexapac

- ethyl at this time primarily because of the low acute inhalation toxicity (Toxicity Category IV). However, there are m ultiple potential sourcesPage 22 of 28



### of post

- application inhalation exposure to individuals performing post

- application activities in previously treated fields. These 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, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in December 2009, and
received the SAP’s fin al 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 as well as available post

- application inhalation exposure data generated by the Agricultural Reentry Ta sk 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 p ut into place, the Agency may revisit the need for a quantitative occupational
post

- application inhalation ex posure assessment for trinexapac

- ethyl

.

Although a quantitative occupational post

- application inhalation exposure assessment was not performed, an inhalation exposure assessment was perfo rmed for occupational handlers. This
assessment resulted in risks that did not exceed HED’s level of concern at baseline inhalation

PPE. Handler exposure resulting from application of pesticides outdoors is likely to result in higher exposure than post

- application exposure. Therefore, it is expected that these handler inhalation exposure estimates would be protective of most occupational post

- application inhalation exposure scenarios.

Restricted Entry Interval: C urrent trinexapac

- ethyl labels have either no REI or a 4 hour REI. The trinexapac

- ethyl technical material has been classified in Toxicity Category III for acute dermal, oral, and primary eye irritation and Category IV for acute inhalation and primary sk in irritation. Per the Worker Protection Standard (WPS), a 12

- hr restricted entry interval (REI) is required for chemicals classified under Toxicity Category III/IV. The R egistration D ivision (RD) should ensure the proper REIs are put in place on the lab els to reflect these requirements

.

Based on HED’s occupational postapplication exposure assessment, REI s for hand

- harvesting

sugarcane were estimate d to be 8 days for short

- term and intermediate

- term exposure

. However, HED does not recommend that REI’s be changed on the trinexapac

- ethyl labels at this time based on two main issues. One, a l most all sugarcane harvesting in the United States is done mechanically. Two, the proposed trinexapac

- ethyl labels have a 28

- day pre

- harvest interval (PHI) for sugarcane so hand harvesting should not occur until after 28 days which is protective

of the estimated REIs.

5.0 RESIDENTIAL (NON

- OCCUPATIONAL) EXPOSURE

Trinexapac

- ethyl is currently registered for use on residential lawns, athletic fields, parks, and golf courses by residential consumers as well as applied by PCOs and commercial applicators; therefore, a residential handler assessment has been completed. The combined dermal plus inhalation risks to residential handlers did not exceed HED’s (LOC) for all scenarios. Short

- term
dermal postapplication risks were assessed for adults, youths, and toddlers and did not exceed HED’s LOC for all residential post

- a pplication scenarios.Page 23 of 28



### 5.1 Residential (Non

- Occupational) 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 sce narios do not use a tiered approach for personal protection using increasing levels of PPE in residential handler risk assessments. Homeowner handler assessments 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 well 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 residential use of trinexapac

- ethyl on lawns. The quantitative exposure/risk assessment developed for residential handlers is based on the following scenarios:

Mixer/Loader/Applicators

Liquid: Low Pressure Handwand; Wettable Powders: Low Pressure Handwand; Liquid: Hose End Sprayer; Liquid: Backpack Sprayer; Granules: Push Type Spreader; and Granules: Belly Grinder

The methods for assessing exposures for residential handlers were based primarily on EPA’s Draft Standard Operating Procedures (SOPs) for Residential Exposure Assessments (December 1997), and updates contained in HED’s Science Adv isory Council Policy 12 (February 2001). According to Table A

- 1 of the SOPs, the method used for estimating residential applicator exposure is believed to produce a central tendency to high

- end estimate of exposure.

Non

- occupational handler’s exposure an d risk est imates are summarized in Table 6 . The combined dermal plus inhalation risks to residential handlers do not exceed HED’s level of concern for all scenarios (i.e., MOEs ≥ 100)

.

Table 6

. Short

- Term Residential Handler Baseline Dermal and Inhalation Exposures

Crop Grouping Target

MOE Dermal

Unit Exposure (mg/lb ai) Inhalation

Unit Exposure (mg/lb ai) Application

Rate a (lb ai/A) Area

Treated Daily b
(acres/day) Baseline Baseline Inhalation Total

Baseline Baseline Dermal

Dose c (mg/kg/day) Dermal

MOE d Dose e MOE f Baseline

Dermal +

Baseline

Inhalation

MOE g

Mixer/Loader/Applicator (Liquids)

- Low Pressure Handwand Application

Turf 100 100 0.03 0.34 0.023 0.01 5800 0.0000039 15000000 5800

Mixer/Loader/Applicator (Wettable Powders)

- Low Pressure Handwand Application

Turf 100 250 1.063 0.34 0.023 0.026 2300 0.00014 430000 2300

Mixer/Loader/Applicator (Liquids)

- Hose End Sprayer ApplicationPage 24 of 28 Turf 100 11 0.017 0.34 0.5 0.025 2400 0.000048 1200000 2400

Mixer/Loader/Applicator (Liquids)

- Backpack Sprayer Application

Turf 100 5.1 0.03 0.34 0.023 0.00053 110000 0.0000039 15000000 110000

Mixer/Loader/Applicator (Granules)

- Push Type Spreader Application

Turf 100 0.67 0.00088 0.44 0.5 0.002 31000 0.0000032 19000000 30000

Mixer/Loader/Applicator (Granules)

- Belly Grinder Application

Turf 100 110 0.062 0.44 0.023 0.015 4000 0.00001 5700000 4000

a. Application rates based on proposed labels

. b. Based on HED Science Advisory Committee Policy 12: Recommended Revisions to the Standard Operating Procedures for Residential Exposure Assessment (February 22, 2001), and on professional judgment.

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 75.5 % dermal absorption / body weight (60 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% inhalation absorption / body weight (60 kg).

e. Dermal MOE = NOAEL ( 6 0 mg/kg/day) / dermal daily dose (mg/ kg/ day). Level of concern = 100.

f. Inhalation MOE = NOAEL ( 6 0 mg/kg/day) / inhalation daily dose (mg/ kg/ day). Level of concern = 100.

g. Combined Dermal + Inhalation MOE = NOAEL ( 60 mg/kg/day) / Combine d dermal + inhalation dose (mg/kg/day).



### 5.2 Residential Post

- Applic ation Exposure and Risk

HED uses the term “post

- application” to describe exposure to individuals that occur as a result of being in an environment that has been previously treated with a pesticide. Trinexapac

- ethyl can be used in many areas that can be f requented by the general population including residential areas (e.g., home lawns, recreational turf). As a result, individuals can be exposed by entering these areas if they have been previously treated. HED refers to these exposures as “residential” in

nature.

Short

- term dermal pos t

- application exposures and risks have been assessed for trinexapac

- ethyl

. There is the potential for incidental oral exposure, however, since there is no point of departure for that route, a quantitative assessment was not conducted. The populations that were considered

in the assessment include:

Residential Adults : these ind ividuals are members of the general population that are exposed to chemicals by engaging in activities at their residences (e.g., in their lawns) and also in areas not limited to their residence (e.g., golf courses or parks) previously treated with a pesti cide. These kinds of exposures are attributable to a variety of activities and are usually addressed by HED in risk assessments by considering a representative activity as the basis for the exposure calculation.

Residential Children : children are members of the general population that can also be exposed in their residences (e.g., on lawns and other residential turfgrass areas). These kinds of exposures are attributable to a variety of activities such as playing outside. Children (ages 3

- 6) have been

sel ected as the representative population for lawn turf assessments. Youth (ages 10

- 12) have been selected as the representative population for golf course turf.

There are several post

- application scenarios associated with the use of trinexapac

- ethyl on

rec reational turf: adults golfing, high contact lawn activities, and mowing and children high

contact lawn activities

. Duration of such recreational exposure is anticipated to be short

- term (<30 days). A short

- term post

- application dermal exp osure/risk estimate for golfing, high contact lawn activities, and mowing was produced based on following assumptions and calculations:Page 25 of 28



### Based on the SOPs for Residential Exposure Assessment and the uses specified in the proposed labels, the following resi dential pos t

- application exposure scenarios are evaluated:

● Dermal Dose from pesticide residues on treated turf: Post

- application exposure calculations for homeowners (adults and children) from skin contact with pesticide residues on treated turf;

The assumptions and factors used in this residential post

- application assessment include:

● HED combines risks resulting from exposures to individual when it is likely they can occur simultaneously based on the use pattern and the behavior associated wi th the exposed population. For this assessment, HED combined risks (i.e., MOEs) for different kinds of exposures within the turf ( dermal ) exposure scenario. These represent the standard set of exposures that are typically added together when chemicals ar e used on turf, because it is logical they can co

- occur.

● Exposures to adults and children on treated turf were addressed using the latest HED standard operating procedures for this scenario including:

o 5 percent of the application rate has been used to calculate the day

- zero TTR residue levels used for assessing risks from dermal and hand

- to

- mou th exposures, since trinexapac

- ethyl specific turf transferable residue study data are not available;

o 20 percent of the application rate has been used to calcul ate the day

- zero residue levels used for assessing risks from object

- to

- mouth behaviors (a higher percent transfer has been used for object

- to

- mouth behaviors, because it involves a teething action believed to be more analogous to DFR/leaf wash sample coll ection where 20 percent is also used);

o 3 to < 6 year old children are expected to weigh 15 kilograms (representing an average weight from years one to six); dermal exposures for playing on treated turf are based on a transfer coefficient of 14,500 cm 2 

### /hr for adults or 5,200 cm 2 

### /hr for children;

o dermal exposures for golfing are based on a transfer coefficient of 500 cm 2 

### /hr for adults;

o exposure duration for the turf grass scenario is estimated to be 2 hours based on information in HED’s Exposure Factors Hand book;

o exposure duration for golfing is estimated to be 4 hours (assuming chemical is used on all parts of a course [greens, tees and fairways] and an adult plays 18 holes of golf)

.

Post

- application exposures/risks from treated turf were calculated using the following equations:

Dermal Exposure to Pesticide Residues on Treated Turf

The approach used to calculate the dermal exposures that are attributable to the contact of pesticide residues on tre ated turf is:

ADD = (TTR 0 

### * CF1* Tc * ET) * DA / BWPage 26 of 28



### w here:

ADD = average daily dose (mg/kg/day);

TTR 0 

### = turf transferable residue on day "0" (μg/cm 2 

### );

CF1 = weight unit conversion factor to convert the μg of residues on the grass to

mg (0.001 mg/μg);

Tc = transfer coefficient (14,500 cm 2 

### /hr for adults, 5,200 cm 2 

### /hr for children );

ET = exposure time (2 hr/day);

DA = dermal absorption factor (100% or 8%); and

BW = body weight (adult = 60 kg, children =15 kg).

and

TTR 0 

### = AR * F * ( 1

- D) 0 

### *CF2 * CF3

w here:

AR = application rate (lb ai/A)

F = fraction of ai retained on turf (5%);

CF2 = conversion rate from pounds active ingredient to micrograms of active

ingredient (4.54E+08 μg/lb); and

CF3 = conversion rate from acres to cm 2 

### (2.47E

- 08 A/cm 2 

### ).

Dermal MOE = NOAEL (60 mg/kg/day ) ADD (mg/kg/day)

The dermal MOEs calculated for adults golfing, mowing and high contact lawn activities are all greater than 100 and therefore, the risk does not exceed HED’s level of concern. The dermal MOEs calculated for children high contact lawn activities is greater than 100 and therefore, the

risk s do not exceed HED’s level of concern.

Although exposure to children golfing could be almost twice that of the adult golfer because of increased surface area/body weight (SA/BW) ratios, younger golfers are not expected to use the golf course for the same length of time as adolescents and adults. The shorter duration on the golf course for younger golfers offsets the higher SA/BW; therefore, risks from short

- term post

application exposures to young golfers are likely to be similar to risks for adult golfers.

The residential post

- application MOEs ranged from 450 to 24 ,000 and therefore do not exceed HED’s level of concern (MOE ≥ 100). A summary of the residential post

- application exposures/risks is presented in Table 7 and 8

.

Table 7

. Short

- and Intermediate

- Term Residential Postapplication Exposure and

Risk Estimates for Trinexapac

- ethyl (Liquids)
Lifestage Postapplication Exposure Scenario Application Rate Dose MOEs

Adult Turf

- sprays High Contact Lawn Activities (Dermal) 0.34 0.071 840Page 27 of 28



### Table 7

. Short

- and Intermediate

- Term Residential Postapplication Exposure and

Risk Estimates for Trinexapac

- ethyl (Liquids)
Lifestage Postapplication Exposure Scenario Application Rate Dose MOEs Golfing (Dermal) 0.17 0.0025 24000 Mowing (Dermal) 0.34 0.0025 24000

Child High Contact Lawn Activities (Dermal) 0.34 0.1 590



### Table 8

. Short

- and Intermediate

- Term Residential Postapplication Exposure and Risk Estimates for Trinexapac

- ethyl (Granular Formulations) Lifestage Postapplication Exposure Scenario Application Rate Dose MOEs

Adult

Turf

- granules High Contact Lawn Activities (Dermal) 0.4 4 0.092 650

Golfing (Dermal) 0.17 0.0025 24000 Mowing (Dermal) 0.4 4 0.0032 19000

Child High Contact Lawn Activities (Dermal) 0.4 4 0.13 450



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

- application inhalation exposure assessment was not performed for trinexapac

- ethyl at this time primarily because of the low acute inhalation toxicity (Toxicity Category IV) . However, volatilization of pesticides may be a potential source of post

- application inhalation exposure to individuals nearby to pesticide applications. The Agency sought expert advice and input on issues related to volatilization of pesticides from it s Federal Insecticide, Fungicide, and Rodenticide Act 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

pr ocess of evaluating the SAP report and may, as appropriate, develop policies and procedures to identify the need for and, subsequently, the way to incorporate post

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

- application inhalation exposure assessment

for trinexapac

- ethyl

.

5.3 Spray Drift

Spray drift is always a potential source of exposure to residents nearby to spraying operations.

This is particularly the case with aerial application, but, to a lesser extent, could also be a potential source of exposure from the ground application metho d employed for trinexapac

- ethyl. The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices (see the Agency’s Sp ray Drift website for more information at http://www.epa.gov/opp00001/factsheets/spraydrift.htm)

. On a chemical by chemical basis

, the Agency is now requiring interim mitigation measures for aerial applications that must be placed on product labels/label ing. The Agency has completed its evaluation of the new data base submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the AgDRIFT computer model to

its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic methods. After the policy is in place, the Agency may impose further refinements in spray drift management practices to reduce off

- target drift and risks associated with aerial as well as otherPage 28 of 28



### application types where appropriate.

Although a quantitative residential post

- application inhalation exposure assessment was not performed as a result of pesticide drift from neighboring treated agricultural fields, an inhalation exposure assessment was performed for occupational flaggers. This exposure scenario is representative of a worse case inhalation (drift) exposure and may be considered protective of most outdoor agricultural and commercial post

- application inha lation exposure scenarios

.

References

Author Barcode Date Title

Kelly Schumacher D356118 9/5/2008 Trinexapac

- ethyl: Revised Human Health Assessment Scoping Document in Support of Registration Review