UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

MEMORANDUM

Date: January 20, 2011

SUBJECT: Fluoxastrobin: Occupational and Residential Exposure Assessment

agricultural uses of fluoxastrobin on 

(Chayote; Chinese waxgourd; Cucumber; Gherkin; Gourd, edible; Pumpkin; 

Squash, summer; and Squash, winter)

PC Code: 028869

Decision No.: 433137

Petition No.: 0F7726

Risk Assessment Type: Single Chemical

TXR No.: NA

MRID No.: NA

FROM: Kristin Rury

Risk Assessment

Health Effects Division (7509P)

THROUGH: Barry O’Keefe, Senior Biologist

Risk Assessment Branch 3

Health Effects 

TO: Nancy Tsaur

Risk Assessment Branch 3

Health Effects Division (7509P)

The Registration Division (RD) requested that 

occupational exposure and risk assessment for new 

cucumber. Note: This memorandum was reviewed by the Exposure Science Advisory

Committee (ExpoSAC) on January 20,

Page 1 of 14

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION

Occupational and Residential Exposure Assessment

agricultural uses of fluoxastrobin on Squash and Cucumber Crop Subgroup 9B 

(Chayote; Chinese waxgourd; Cucumber; Gherkin; Gourd, edible; Pumpkin; 

Squash, summer; and Squash, winter).

DP Barcode: 380848

Registration No.: 66330-64,

Regulatory Action: Section 3

Single Chemical Case No.: NA

CAS No.: 193740-76-0

40 CFR: 180.609

Kristin Rury, Biologist

isk Assessment Branch 3

Health Effects Division (7509P)

Barry O’Keefe, Senior Biologist

Risk Assessment Branch 3

Health Effects Division (7509P)

Nancy Tsaur, Risk Assessor

Risk Assessment Branch 3

Health Effects Division (7509P)

Registration Division (RD) requested that the Health Effects Division (HED) conduct an 

exposure and risk assessment for new proposed uses of fluoxastrobin

Note: This memorandum was reviewed by the Exposure Science Advisory

January 20, 2011.

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

Occupational and Residential Exposure Assessment for proposed 

Cucumber Crop Subgroup 9B 

(Chayote; Chinese waxgourd; Cucumber; Gherkin; Gourd, edible; Pumpkin; 

(HED) conduct an 

fluoxastrobin on squash and 

Note: This memorandum was reviewed by the Exposure Science Advisory
Page 2 of 14

1.0 EXECUTIVE SUMMARY

Fluoxastrobin is a strobilurin class active ingredient (ai) that is proposed for use as a broadspectrum fungicide. The new proposed uses of fluoxastrobin are for control of certain diseases 

on squash and cucumber crop subgroup 9B (Chayote; Chinese waxgourd; Cucumber; Gherkin; 

Gourd, edible; Pumpkin; Squash, summer; and Squash, winter). The proposed formulated enduse product evaluated in this assessment is labeled under the trade name Fluoxastrobin 480 SC 

Fungicide (EPA Reg. No. 66330-64), which contains 40.3% (i.e., 4 lbs ai/gallon) fluoxastrobin, 

and serves as the master label for Evito® 480 SC fungicide, DISARMTM 480 SC Fungicide, and 

Fluoxastrobin 480 SC Fungicide Seed Treatment, produced by Arysta LifeScience North 

America, LLC (Arysta). In this memorandum, the name fluoxastrobin will be used for the ai in 

this product.

Proposed Use Profile:

Broadcast foliar applications of fluoxastrobin may be applied to squash and cucumber crop 

subgroup 9B at a maximum application rate of 0.16 lb ai/A for both foliar and soil-borne 

diseases. For all of crop subgroup 9B, handlers may apply fluoxastrobin using groundboom

equipment only. The maximum application rate is 0.68 lb ai per year with a maximum of 4 

applications per season and a minimum application interval of 7 days between applications. 

Exposure Profile:

There is a potential for short- and intermediate-term occupational exposure to fluoxastrobin

during mixing, loading, application, and other handling tasks and for short- and intermediateterm occupational exposure during post-application activities. Chronic exposure is not expected 

for the proposed use patterns associated with fluoxastrobin. 

Hazard Profile: 

A short-term dermal endpoint was not identified; therefore, only intermediate-term dermal risks 

as well as short- and intermediate-term inhalation risks were assessed. The estimated dermal and 

inhalation exposures were compared to the oral No Observed Adverse Effect Level (NOAEL) of 

3.0 mg/kg/day from a 90 day subchronic feeding dog study in which dose-related reductions in 

net body weight gain and food efficiency, in addition to toxicity findings in the liver (cholestasis) 

of both sexes, and kidneys (increased relative weights in females and degeneration of the 

proximal tubular epithelium in males), were observed at the Lowest Observed Adverse Effect 

Level (LOAEL) of 24.8 mg/kg/day for males and 24.2 mg/kg/day for females. Because this 

endpoint is from an oral study, the estimated dermal exposures were adjusted by applying a 2.3%

dermal absorption factor. Since no inhalation absorption data are available, toxicity by the 

inhalation route is considered to be equivalent to the estimated toxicity by the oral route of 

exposure. This endpoint is not a developmental effect; therefore, a 70-kg body weight was used 

in the calculations. Resulting intermediate-term risk estimates were combined into total risk 

estimates because the same endpoint was chosen to evaluate both routes of exposure. The level 

of concern (LOC) for occupational risk is for margins of exposure (MOEs) of 100 (i.e., an MOE 

< 100 is of concern). Fluoxastrobin is characterized as “not likely to be carcinogenic to humans” 

based on the lack of increased tumor incidence in the rat and mouse carcinogenicity studies;
Page 3 of 14

therefore, cancer risks were not assessed.

Occupational Exposure & Risk Estimates:

Agricultural Handlers:

No chemical-specific handler exposure data were submitted in support of this registration. It is 

the policy of HED to use data from the Pesticide Handlers Exposure Database (PHED) Version 

1.1 as presented in PHED Surrogate Exposure Guide (8/98) to assess handler exposures for 

regulatory actions when chemical-specific monitoring data are not available (HED ExpoSAC 

Standard Operating Procedure (SOP) No. 7, dated 1/28/99). The results of the occupational 

handler exposure and risk assessment indicate that MOEs were greater than the level of concern 

(LOC = 100) at some level of risk mitigation. 

Dermal

For all handler mixing, loading, and applying scenarios, the intermediate-term dermal risks do 

not exceed HED’s level of concern with baseline attire (i.e., long-sleeve shirt, long pants, shoes, 

and socks) or baseline attire plus chemical resistant gloves. With baseline attire, the dermal 

MOE for mixer/loaders was 250, and the MOE for applicators was 17,000. With baseline attire 

plus chemical resistant gloves, the dermal MOE for mixer/loaders was 31,000 and the MOE for 

applicators was 51,000. 

Inhalation

The short- and intermediate-term inhalation risks to handlers do not exceed HED’s level of 

concern at baseline (no respirator) for any of the handler scenarios. With baseline attire (no 

respirator) the inhalation MOE for mixer loaders was 14,000 and the MOE for applicators was 

22,000,000. 

Combined

Combined dermal and inhalation risks do not exceed HED’s level of concern with baseline attire 

or baseline attire plus chemical resistant gloves. With baseline attire, the combined (dermal + 

inhalation) MOE for mixer/loaders was 240 and the MOE for applicators was 17,000. With 

baseline attire plus chemical resistant gloves, the combined (dermal + inhalation) MOE was 

9,500 for mixer/loaders and 51,000 for applicators. 

Agricultural Post-Application:

Based on HED's current practices, a quantitative occupational post-application inhalation 

exposure assessment was not performed for fluoxastrobin at this time. However, there are 

multiple potential sources of post-application inhalation exposure to individuals performing postapplication activities in previously treated fields. If new policies or procedures are put into 

place, HED may revisit the need for a quantitative occupational post-application inhalation 

exposure assessment for fluoxastrobin.

Intermediate-term dermal post-application exposures and risks to occupational workers were 

estimated using standard values established by HED since no chemical-specific data were 

submitted. Using HED default assumptions and default DFR values, all scenarios resulted in 

MOEs greater than 100 on day 0 (12 hours after application), and therefore, risks do not exceed 
Page 4 of 14

HED’s level of concern. 

The restricted entry interval (REI) is currently based on the acute toxicity of fluoxastrobin

technical material. Fluoxastrobin is classified as Toxicity Category III by the dermal route and 

for eye irritation potential and Toxicity Category IV for skin irritation potential. Under the 

Worker Protection Standard for Agricultural Pesticides, active ingredients classified as acute 

toxicity categories III or IV for these routes are assigned a 12-hour REI. Therefore, the 12-hour 

REI that appears on the proposed label is adequate for protection of the exposed workers.

Review of Human Research:

This risk assessment relies in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These studies, which comprise the PHED, 

have been determined to require a review of their ethical conduct and have received that review.

Residential Exposure:

This document presents the assessment of proposed agricultural uses of fluoxastrobin. No 

residential uses are being requested at this time; therefore, no residential handler exposure and 

risk assessment has been conducted in this document. However, uses on turf and ornamentals 

are currently registered on fluoxastrobin labels.

2.0 HAZARD CHARACTERIZATION

The quality of the toxicology database for fluoxastrobin is good and the confidence in the hazard 

and dose-response assessments is high. The toxicity database for fluoxastrobin is considered 

adequate to support toxicity endpoint selection for risk assessment and for FQPA evaluation. 

However, under the current 40 CFR §158.500 data requirement guidelines, the immunotoxicity

data (OPPTS 780.7800) is required as a condition of registration. HED determined that the 10X 

FQPA safety factor for the protection of infants and children should be removed for all potential 

exposure scenarios to fluoxastrobin because the toxicity database is adequate, there are no 

residual uncertainties for pre- and/or postnatal toxicity, and the doses chosen as quantitative risk 

estimates are adequately protective for infants and children. Additionally, exposure data are 

complete or are estimated based on data that reasonably account for potential exposures. Based 

on these data and conclusions, the FQPA safety factor can be reduced to 1X. 

To address the immunotoxicity data requirements as presented in the 40 CFR Part 158, HED

examined the entire toxicity database of fluoxastrobin; the database of this chemical does not 

show clear evidence of biologically relevant effects on the immune system that relate to this 

chemical. The overall weight of evidence suggests that this chemical does not directly target the 

immune system. An immunotoxicity study in the mouse is available; the results of this study

show no apparent decrease on B-cell activated, T-cell mediated IgM response to sheep red blood 

cell (SRBC) at doses as high as 2383 mg/kg/day. However, this study has many deficiencies 

including uncertainty in dietary test material intake, and the study is classified as unacceptable. 

At this time, HED does not believe that conducting a new functional immunotoxicity study will 

result in a lower NOAEL than the regulatory dose for risk assessment, and an additional factor 

for database uncertainty (UFDB) is not needed to account for lack of this study.
Page 5 of 14

HED’s LOC for the MOE is defined by the uncertainty factors that are applied to the assessment. 

HED applies a 10X factor to account for interspecies extrapolation and a 10X factor to account 

for intraspecies sensitivity. The total uncertainty factor that has been applied to the non-cancer 

risk assessment for fluoxastrobin is 100 for occupational exposure. Occupational exposure and 

risk resulting in MOEs greater than or equal to 100x will not exceed HED’s level of concern.

The acute toxicity for fluoxastrobin is summarized in Table 1. Fluoxastrobin has a low order of 

acute toxicity based on its classification in Toxicity Category III via the oral and dermal routes, 

and Toxicity Category IV by the inhalation route of exposure. Fluoxastrobin is a moderate eye 

irritant (Toxicity Category III), but is neither a dermal irritant nor a sensitizer.

Table 1: Acute Toxicity Profile - Fluoxastrobin

Guideline No. Study Type MRID(s) Results Toxicity Category

870.1100 Acute oral - rat 45865612 LD50>2000 mg/kg III

870.1200 Acute dermal - rat 45865613 LD50>2000 mg/kg III

870.1300 Acute inhalation - rat 45865618 LC50 = 4.9 mg/L IV

870.2400 Acute eye irritation - rabbit 45865620 moderate irritant III

870.2500 Acute dermal irritation - rabbit 45865622 not an irritant IV

870.2600 Skin sensitization - guinea pig 45865624 not a sensitizer -

Exposures to occupational handlers are expected to be short- and intermediate-term in duration 

via the dermal and inhalation routes. Exposures to occupational post-application workers are 

expected to be short- and intermediate-term in duration via the dermal route. A short-term 

dermal endpoint was not identified; therefore, only intermediate-term dermal risks were 

assessed. For the other routes of exposure, the same point of departure (PoD) was selected from 

a 90-day subchronic dog study (i.e., NOAEL of 3 mg/kg/day), based on dose-related reductions 

in net body weight gain and food efficiency in addition to toxicity findings in the liver 

(cholestasis) in both sexes and kidneys (increased relative weights in females and degeneration 

of the proximal tubular epithelium in males). Because this is an oral study, dermal doses were 

adjusted to account for 2.3% dermal absorption, and inhalation doses were calculated assuming 

100% absorption. Resulting dermal and inhalation MOEs were combined into total MOEs 

because the same endpoint was chosen to evaluate both routes of exposure. The endpoints and 

PoDs selected for fluoxastrobin are shown in Table 2. 
Page 6 of 14

Table 2: Summary of Toxicological Doses & Endpoints for Fluoxastrobin for Use in Occupational Risk 

Assessments

Exposure

Scenario

Point of Departure

Uncertainty/FQPA 

Safety Factors and 

Level of Concern

Study and Toxicological Effects

Dermal 

Short-Term

(1 - 30 days)

N/A None None: A 28-day dermal toxicity study 

in the rat is negative up to the limit 

dose and there are no developmental or 

neurotoxicity concerns

Dermal 

Intermediate-Term

(1 - 6 months)

NOAEL = 3.0 

mg/kg/day 

dermal absorption 

rate = 2.3%

UFA = 10X

UFH = 10X

FQPA SF = 1X

LOC for MOE = 100

90 Day Subchronic Dog

LOAEL = M/F 24.8/24.2 mg/kg/day 

(800 ppm) based on dose-related 

reductions in net body weight gain and 

food efficiency in addition to toxicity 

findings in the liver (cholestasis) in 

both sexes and kidneys (increased 

relative weights in females and 

degeneration of the proximal tubular 

epithelium in males).

Inhalation 

Short-Term

(1 - 30 days) and 

Intermediate-Term

(1 - 6 months)

NOAEL = 3 .0 

mg/kg/day 

Inhalation absorption 

rate = 100%

UFA = 10X

UFH = 10X

FQPA SF = 1X

LOC for MOE = 100

90 Day Subchronic Dog

LOAEL = M/F 24.8/24.2 mg/kg/day 

(800 ppm) based on dose-related 

reductions in net body weight gain and 

food efficiency in addition to toxicity 

findings in the liver (cholestasis) in 

both sexes and kidneys (increased 

relative weights in females and 

degeneration of the proximal tubular 

epithelium in males).

Cancer (oral, 

dermal, inhalation)

Classification: Not Likely to be carcinogenic to humans.

NOAEL = no observed adverse effect level. LOAEL = lowest observed adverse effect level. FQPA SF = FQPA 

Safety Factor. UF = uncertainty factor. UFA = extrapolation from animal to human (intra-species). UFH = potential 

variation in sensitivity among members of the human population (inter-species). MOE = margin of exposure. LOC 

= level of concern. N/A = not applicable.

3.0 PROPOSED USE PATTERNS

Table 3 provides a summary of the proposed uses of fluoxastrobin.
Page 7 of 14

Table 3: Use Profile for Fluoxastrobin for use on Squash and Cucumber

Crop Product 

Information Application Method of Application

Maximum 

Single 

Application 

Rate (lb 

ai/A)

Maximum 

Number of 

Applications 

(oz)

Retreatment 

Interval 

(RTI)

Maximum 

Seasonal 

Application 

Rate

Squash/Cucumber 

Crop Subgroup 9B 

(Chayote; Chinese 

waxgourd; 

Cucumber; Gherkin; 

Gourd, edible; 

Pumpkin; Squash, 

summer; and Squash, 

winter)

EVITO® 480 

SC Fungicide 

EPA Reg. No. 

66330-64, 4 lb 

fluoxastrobin 

per gallon

Foliar 

Disease

Groundboom 

Only 0.16 4

7-14 days

0.68

Soilborne 

Disease 7 days

4.0 OCCUPATIONAL EXPOSURE/RISK PATHWAY

4.1 Handler Exposure

Fluoxastrobin can be applied to crop subgroup 9B using groundboom application equipment. 

Application methods, maximum application rates, and use sites are summarized in Table 3. 

Handler exposure is expected to be short- or intermediate-term based on information provided on 

proposed labels. 

The quantitative exposure/risk assessment for occupational handlers is based on the following 

exposure scenarios: 

Mixer/Loaders:

1. Mixing/loading liquid concentrate to support groundboom applications, and

Applicators:

2. Applying sprays with groundboom equipment.

4.1.1 Data and Assumptions for Handler Exposure Scenarios

Unit Exposures:

Chemical-specific data for assessing exposure during pesticide handling activities 

(mixing/loading, and applying) were not submitted to the Agency in support of this Section 3 

application. It is HED policy to use data from the PHED Version 1.1 to assess handler exposures 

for regulatory actions when chemical-specific data are not available (ExpoSAC, SOP No.7, 

January 1999).

Mitigation Approaches:

The baseline clothing level for occupational exposure scenarios is generally an individual 

wearing long pants, a long-sleeved shirt, shoes, socks, no chemical-resistant gloves, and no 
Page 8 of 14

respirator. The first level of mitigation generally applied is personal protective equipment (PPE), 

which may include addition of chemical resistant-gloves (as specified on the proposed label), an 

additional layer of clothing, and/or a respirator. The next layer of mitigation considered in the 

risk assessment process is the use of appropriate engineering controls, which, by design, attempt 

to eliminate the possibility of human exposure. Examples of commonly used engineering 

controls include enclosed cockpits or tractor cabs, closed mixing/loading systems, and watersoluble packets.

Occupational handler exposure assessments were completed by HED using baseline clothing 

attire, and baseline clothing attire plus gloves.

Area Treated:

Based on HED ExpoSAC SOP No. 9.1, the area treated in a day was assumed to be 80 acres for 

mixing, loading and applying fluoxastrobin with groundboom equipment to crop subgroup 9B.

Application Rate:

Broadcast foliar applications of fluoxastrobin may be applied at a maximum application rate of 

0.16 lb ai/A for crop subgroup 9B. Application rates are shown in Table 3. 

Body Weight:

The average adult body weight of 70 kg was used for estimating dermal and inhalation doses, 

since the selected toxicological endpoints are not based on a developmental effect.

Absorption Factors:

Since the intermediate-term dermal endpoint was based on an oral study (90 day subchronic 

feeding study in the dog), a dermal absorption factor of 2.3% was used to estimate dermal 

exposure for intermediate-term durations. The results of a preliminary dermal study (MRID 

45911501) clearly showed that following intravenous administration, fluoxastrobin is rapidly and 

nearly totally excreted in the urine and feces within 48 hours (allowing for 100% bioavailability). 

Following an 8-hour dermal application in a male monkey, absorption was negligible (1.16% 

preliminary, 2.16% main). The normalized absorption value for the main study (MRID 

45911502) was 2.31%. Therefore, HED set the dermal absorption value at 2.3% for risk 

assessment purposes.

Since the short- and intermediate-term inhalation endpoint was based on an oral study (90 day

subchronic feeding study in the dog) and no inhalation absorption data are available, toxicity by

the inhalation route is considered to be equivalent to the estimated toxicity by the oral route of 

exposure (100% absorption factor). 

Equations and Calculations:

Daily Exposure: Daily handler exposures are estimated for each applicable handler task with the 

application rate, the amount of acres treated in a day, and the applicable unit exposure using the 

following formula:
Page 9 of 14

Daily Exposure (mg ai/day) = Unit Exposure (μg ai/lb ai handled) x Application Rate (lbs ai/) x Daily 

Amount Handled (lbs/day) x Conversion Factor (mg/1,000 μg)

Where: 

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

available for dermal absorption or amount inhaled that is available for 

inhalation absorption,

Unit Exposure = Unit exposure value (μg ai/day),

Application Rate = Normalized application rate based on a logical unit treatment, such as acres; 

maximum values are used (lb ai/acre), and

Daily Amount Handled = Normalized application area based on a logical unit treatment such as acres 

(A/day). 

Daily Dose: Daily dose (inhalation or dermal) was calculated by normalizing the daily dermal 

or inhalation exposure value by body weight and accounting for dermal and inhalation 

absorption. 

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

Body Weight (kg)

Daily Exposure (mg ai/day) = daily unit exposure (mg/lb ai) x application rate (lb ai/A) x acres treated (A/day)

Where:

Average Daily Dose = Absorbed dose received from exposure to a pesticide in a given 

scenario (mg pesticide active ingredient/kg body weight/day),

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

available for dermal absorption or amount 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, and

Body Weight = Body weight determined to represent the population of interest in a risk

assessment.

Margin of Exposure (MOE): The daily dermal dose and daily inhalation dose received by 

occupational handlers were compared to the appropriate point of departure (i.e., NOAEL) to 

assess the risk to occupational handlers for each exposure route. All MOE values were calculated 

separately for dermal and inhalation exposure levels using the following formula:

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 (ADD) is absorbed dose received from exposure to 

pesticide, and

NOAEL = Dose level in a toxicity study, where no observed adverse effects occurred in the 

study.
Page 10 of 14

Combined Risks: Dermal and inhalation risks for 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 formula:

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

4.1.2 Handlers Exposure and Risk

Summaries of the risks for occupational handlers are included in Table 4. The maximum 

application rate for each exposure scenario is presented as the worst-case scenario. All handler 

scenarios resulted in MOEs greater than the level of concern (LOC = 100) at some level of risk 

mitigation. 

Dermal

For all handler mixing, loading, and applying scenarios, the intermediate-term dermal risks do 

not exceed HED’s level of concern with baseline attire (i.e., long-sleeve shirt, long pants, shoes, 

and socks) or baseline attire plus chemical resistant gloves. With baseline attire, the dermal 

MOE for mixer/loaders was 250, and the MOE for applicators was 17,000. With baseline attire 

plus chemical resistant gloves, the dermal MOE for mixer/loaders was 31,000 and the MOE for 

applicators was 51,000. 

Inhalation

The short- and intermediate-term inhalation risks to handlers do not exceed HED’s level of 

concern at baseline (no respirator) for any of the handler scenarios. With baseline attire (no 

respirator) the inhalation MOE for mixer loaders was 14,000 and the MOE for applicators was 

22,000,000. 

Combined

Combined dermal and inhalation risks do not exceed HED’s level of concern with baseline attire 

or baseline attire plus chemical resistant gloves. With baseline attire, the combined (dermal + 

inhalation) MOE for mixer/loaders was 240 and the MOE for applicators was 17,000. With 

baseline attire plus chemical resistant gloves, the combined (dermal + inhalation) MOE was 

9,500 for mixer/loaders and 51,000 for applicators. 
Page 11 of 14

Table 4: Baseline and PPE Short-Term Exposure and Risk Estimates (MOE) for Occupational Application of Fluoxastrobin

Exposure 

Scenario

App Rate 

(lb ai/A)1

Acres 

Treated 

Daily2

Dermal 

Unit 

Exposure 

(mg/lb ai)

PPE-G 

Dermal 

Unit 

Exposure 

(mg/lb ai)

Inhalation 

Unit 

Exposure 

(mg/lb ai)

Dose 

Baseline 

Dermal3

PPE 

Dermal 

Dose3

Dose 

Baseline 

Inhalation4

MOE 

Baseline 

Dermal5

MOE 

PPE 

Dermal5

MOE 

Baseline 

Inhalation5

Combined 

Baseline 

MOE6

Combined 

PPE 

MOE6

Mixer/Loader

Mixing and 

Loading Liquid 

Formulation 

for 

Groundboom 

Application 

(PHED)

0.16 80 2.9 0.023 0.0012 0.012 0.00010 0.0002194 250 31,000 14,000 240 9,500

Applicator

Groundboom 

Application 

(PHED)

0.16 80 0.041 0.014 0.00074 0.000172 0.0000588 0.000000135 17,000 51,000 22,000,000 17,000 51,000

1 Application rate is based on maximum values found in proposed label (EPA Reg. 66330-65).

2 Area treated is based on the area that can be reasonably treated in a single day based on the application method (standard EPA/OPP/HED values)

3 Daily Dermal Dose (mg/kg/day) = (Unit Exposure x Application rate x Area treated x Dermal Absorption Factor) 2.3% / 70 kg.

4 Daily Inhalation Dose (mg/kg/day) = (Unit Exposure x Application rate x Area treated x inhalation absorption factor 100%) / 70 kg.

5 Short- and Intermediate-Term MOE = NOAEL (3 mg/kg/day) / Daily Dose. The LOC is 100.

6 Combined MOE = 1/(1/Dermal MOE + 1/Inhalation MOE)
Page 12 of 14

4.2 Postapplication Exposure

4.2.1 Data and Assumptions for Post-application Exposure Scenarios

There is the possibility for agricultural workers to have post-application dermal exposure to

fluoxastrobin following its proposed agricultural crop uses. Therefore, occupational 

intermediate-term dermal post-application risks were assessed.

There were no chemical-specific DFR data to assess post-application risks to workers while 

performing tasks related to crops treated with fluoxastrobin. Occupational post-application 

exposures and risks were assessed using HED’s default assumptions that 20% of the initial 

application is available for transfer on day 0 (i.e., 12 hours after application) and that the residue 

dissipates at a rate of 10% per day.

HED uses a concept known as the transfer coefficient (TC) to numerically represent the postapplication exposures one would receive (generally presented as cm2

/hour). A TC is a measure 

of the residue transferred from a treated surface to a person who is doing a task or activity in a 

treated area. These values are the ratio of an exposure for a given task or activity to the amount 

of pesticide residue on treated surfaces available for transfer. HED has developed a series of 

standard transfer coefficients that are unique for a variety of job tasks or activities that are used 

in lieu of chemical- and scenario-specific data. HED used Policy 003.1 Science Advisory 

Council for Exposure Policy Regarding Agricultural Transfer Coefficients to estimate transfer 

coefficients for the various tasks that post-application workers might perform on each crop 

grouping. 

HED assumes an 8 hour workday for post-application workers and assumes 70 kg for an adult 

(average adult weight) since the endpoint is not based on developmental effects.

For fluoxastrobin, the exposure durations for non-cancer post-application risk assessment were 

short-term and intermediate-term. However, since there is no toxicological point of departure for 

short-term dermal exposures, post-application risks are presented only for intermediate-term 

dermal exposures. The LOC for occupational post-application risk is for MOEs of 100 (i.e., an 

MOE < 100 is of concern). 

Daily dermal exposures were calculated on each post-application day after application using the 

following equation:

DE(t) (mg/day) = (DFR(t) (μg/cm2) x TC (cm2/hr) x Hr/Day) x DA / 1,000 (μg/mg)

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,

DFR(t) = Dislodgeable foliar residue at time “t” (μg/cm2),

TC = Transfer Coefficient (cm2/hour),

 Hr/day = Exposure duration meant to represent a typical workday (8 hours), and

 DA = Dermal absorption factor (0.023)
Page 13 of 14

Where:

Default DFR (μg/cm2) = AR (lb ai/A) x F x (1- D)tx CF1 x CF2

AR = Maximum application rate,

F = Fraction of ai retained on the foliage,

D = Fraction of residue that dissipates daily,

t = Postapplication day, 

CF1 = 4.54E+8 μg/lb, and

CF2 = 2.47E-8 A/cm2.

4.2.2 Agricultural Exposure and Risk

The post-application exposure associated with agricultural crops is summarized in Table 5. 

Using HED default assumptions, maximum transfer coefficients, and surrogate DFR data, all 

scenarios resulted in MOEs greater than 100 on day 0 (12 hours after application) and, therefore,

were not of concern to HED. 

Table 5: Occupational Post-application Exposure to Proposed Uses of Fluoxastrobin

Crop

Maximum 

Proposed 

Application 

Rate (lb 

ai/A)

Activity Foliage 

Development

TC

(cm2/hr)

Days 

After 

Treatment

DFR1

(ug/cm2)

Daily Dose 

(mg/kg/d)2 MOE3

Squash/Cucu

mber Crop 

Subgroup 9B 

(Chayote; 

Chinese 

waxgourd; 

Cucumber; 

Gherkin; 

Gourd, edible; 

Pumpkin; 

Squash, 

summer; and 

Squash, winter)

0.16

Irrigation, 

scouting, 

hand 

weeding

Full 1500 0 0.3588416 0.0014 2,100

0.16

Hand 

Harvest, leaf 

pulling hand 

pruning

Low 2500 0 0.3588416 0.0024 1,300

0.16

Irrigation, 

scouting, 

thinning, 

hand 

weeding

Low 500 0 0.3588416 0.00047 6,400

1 Default DFR (μg/cm2) = application rate (lb ai/A) x (1- daily dissipation rate) tx 4.54E8 μg/lb x 2.47E-8 A/cm2x 20% DFR after initial 

treatment.

2 Daily Dermal Dose = [DFR (μg/cm2) x TC x 0.001 mg/μg x 8 hrs/day x DA] x (body weight (70 kg)).

3 MOE = NOAEL/Daily Dose (Adult Dermal NOAEL = 100 mg/kg/day).

Restricted Entry Interval: The restricted entry interval (REI) is based on the acute toxicity of 

fluoxastrobin technical material. Fluoxastrobin is classified as Toxicity Category III by the 

dermal route and for eye irritation potential and Toxicity Category IV for skin irritation potential. 

Under the Worker Protection Standard for Agricultural Pesticides, active ingredients classified as 

acute toxicity categories III or IV for these routes are assigned a 12-hour REI. Therefore, the 12-

hour REI that appears on the proposed label is adequate.

5.0 RESIDENTIAL EXPOSURE
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Fluoxastrobin is registered for use in residential settings on turfgrass for use by residential 

handlers. Risks for fluoxastrobin application to turf was previously assessed and did not result in 

risks of concern (K. Rury D371251, 3/4/2010). Therefore, a revised assessment for residential 

handlers was not required. Residential handler combined dermal + inhalation risks resulted in 

MOEs that ranged from 3,200 to 520,000. Post-application incidental oral risks to children 

resulted in an MOE of 1,600 for object-to-mouth exposure, 120,000 for ingestion of treated soil,

and MOEs that ranged from 400 to 850 for hand-to-mouth exposure. Adult dermal postapplication risks resulted in MOEs that ranged from 1,100 to 16,000 from contact with treated 

turf, and the risk from child dermal contact with treated turf resulted in an MOE of 670. 

6.0 RESIDENTIAL BYSTANDER POST APPLICATION & SPRAY DRIFT

Based on the Agency's current practices, a quantitative post-application inhalation exposure 

assessment was not performed for fluoxastrobin at this time. 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 its 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) and is 

in the process of evaluating the SAP report. The Agency may, as appropriate, develop policies 

and procedures to identify the need for and, subsequently, the way to incorporate postapplication 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 fluoxastrobin.

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 method employed for pyraflufen-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. The Agency is now requiring interim mitigation measures for aerial 

applications that must be placed on product labels/labeling. 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 other application types where appropriate.