Date: 

Subject: 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

December 4, 20 15 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

Azoxystrobin. Occupational and Residential Registration Review Risk 

Assessment for the Existing Uses of Azoxystrobin. 

PC Code: 1288 10 

Decision No.: 511551 

DP Barcode: 0430444 

Regula tory Action: Registration Review 

Risk Assessment Type: Occupational/Residential Exposure Assessment Case No.: 7020 

TXR No.: NA CAS No.: 131860-33-8 

MRIO No.: NA 40 C FR: § 180.507 

From: 

Through: 

To: 

Kristin 

Risk Assess

Rury, 

ment 

Biol

Bran

ogist 

ch 

Y--

Ill (

~ Mihrd 

Health Effects Division (7509P) 

And r,-~ C~ r:=7,.P Timothy C. Dole, Industrial Hygienist I J..AJ 'I 

Risk Assessment and Science Support Branch (RASS ) 

Antimicrobials Division (751 OP) 

Barry O'Kecfe, Senior Biologist 

Risk Assessment Branch III (RAB III) 

Health Effects Division (7509P) 

13, o~ 

and (), JJ ¥ --- Shalu Shelat, Environmental Health Scientist t:/ vfl-(f.~ Cassi Walls, Senior Biologist ~>~ l Ur.MU:> 

Exposure Science Advisory Committee (ExpoSAC) I HED 

Veronica Dutch, Chemical Review Manager (CRM) 

Jill Bloom, Team Leader 

Risk Management and Implementation Branch V (RMIB V) 

Division (7508P) 

Page I of64 
Introduction 

The Health Effects Division (HED) and the Antimicrobials Division (AD) of the Office of 

Pesticide Programs (OPP) is charged with estimating the risk to human hea lth from exposure to 

pesticides. As part of Registration Review, the Pesticide Re-evaluation Division (PRO) of OPP 

has requested that HEO and AO evaluate the hazard and exposure data and conduct occupationa l 

and residential exposure assessments, as needed, to estimate the risk to human health that will 

result from the registered uses of azoxystrobin. This memorandum serves as HED·s Registration 

Review exposure and risk assessment of the registered conventional and antimicrobial uses of 

azoxystrobin. 

Azoxystrobin is currently registered for use on a large number of agricultural crops, for seed 

treatment and post-harvest uses on agricultural commodities, as well as for use in indoor and 

outdoor residential areas. 

It is HEO policy to use the best available data to assess exposure. Several sources of generic 

data were used in this assessment as surrogate data in the absence of chemical-specific data, 

including: Pesticide Handlers Exposure Database Version I.I (PHED I.I ); and the Agricultural 

Handler Exposure Task Force (AHETF) database; the Antimicrobial Exposure Assessment Task 

Force (AEATF); ExpoSAC Policies 14, 15, and 15. 1 (SOPs for Seed Treatment); and the 

Residential SOPs (Residential Handlers). Some of these data are proprietary, and subj ect to the 

data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). 

Note: This memorandum was reviewed by the Exposure Science Advisory Committee 

(ExpoSAC) on December 3, 20 15. 

Page 2 of64 
Page 3 of 64

Table of Contents

1.0 Executive Summary.................................................................................................................. 4

2.0 Risk Assessment Conclusions and Recommendations............................................................. 7

2.1 Summary of Risk Estimates.................................................................................................. 7

2.2 Label Recommendations from Occupational Assessment.................................................... 9

2.3 Label Recommendations from Residential Assessment....................................................... 9

3.0 Hazard Characterization.......................................................................................................... 10

4.0 Use Profile .............................................................................................................................. 13

5.0 Residential Exposure and Risk Estimates............................................................................... 17

5.1 Residential Handler Exposure/Risk Estimates.................................................................... 17

5.2 Residential Post-application Exposure/Risk Estimates ...................................................... 21

5.3 Residential Risk Estimates for Use in Aggregate Assessment .......................................... 25

6.0 Non-Occupational Spray Drift Exposure and Risk Estimates................................................ 26

7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates..... 27

8.0 Occupational Exposure and Risk Estimates ........................................................................... 27

8.1 Occupational Handler Exposure/Risk Estimates – Conventional Azoxystrobin Uses....... 27

8.2 Occupational Handler Exposure/Risk Estimates – Antimicrobial Uses............................. 43

8.3 Occupational Post-application Exposure/Risk Estimates................................................... 44

8.3.1 Occupational Post-application Inhalation Exposure/Risk Estimates........................... 44

8.3.2 Occupational Post-application Dermal Exposure/Risk Estimates............................... 46

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms..................... 48

Appendix B. TTR and DFR Data Requirements......................................................................... 58

Appendix C. Exposure Inputs and Inhalation Doses for Registered Conventional Uses of 

Azoxystrobin................................................................................................................................. 60
Page 4 of 64

1.0 Executive Summary

HED and AD have conducted an occupational and residential exposure assessment for 

Registration Review of the active ingredient (ai), azoxystrobin. Azoxystrobin is a βmethoxyacrylate fungicide currently registered for use on a variety of field, vegetable, fruit, and 

nut crops as well as on ornamental plants and turf. It is also used to control mold on indoor 

surfaces. Its biochemical mode of action is inhibition of electron transport. 

This memorandum contains HED’s and AD’s occupational exposure and risk estimates to 

pesticide handlers (i.e., mixers, loaders, applicators) and to agricultural workers conducting postapplication activities. The residential scenarios for aggregate risk assessment have not changed 

since the previous azoxystrobin exposure assessment which reflects HED’s 2012 Residential 

SOPs1( (K. Rury, D418012 and D423847, 12/17/2014). However, the inhalation point of 

departure (POD) has been revised by the risk assessment team since the previous assessment; 

therefore, the conventional and antimicrobial inhalation scenarios have been reevaluated to 

incorporate changes to the azoxystrobin toxicity database. This assessment also contains a nonoccupational post-application assessment evaluating the exposure resulting from azoxystrobin 

drift from agricultural applications onto residential areas. 

Use Pattern

Azoxystrobin is currently formulated as liquid, dry flowable, granule, and dust end-use products 

(EUPs) containing between 0.31% and 50% ai. Azoxystrobin is registered for agricultural use on 

numerous fruit and vegetable crops growing in both fields and greenhouses. Azoxystrobin is 

also registered as a post-harvest treatment for use on bananas, plantains, citrus, and tuberous and 

corm vegetables. It may also be used on golf course turf, lawns, sports fields, ornamentals, 

conifers, roses, cut flowers, interior plantscapes, and sod. Seed treatment uses of azoxystrobin 

include the following commodities: barley; Brassica (cole) leafy vegetables, crop group 5; bulb 

vegetables, crop group 3; canola; corn (field, pop, sweet); cotton; cucurbit vegetables, crop group 

9; eggplant; leafy vegetables, crop group 4; leaves of root and tuber vegetables, crop group 2; 

legume vegetables (succulent or dried), crop group 6; okra, peanut; peppers; potato; rice; root 

vegetables, crop subgroup 1A; soybean; sunflower; tomato; triticale; tuberous and corm 

vegetables (except potato), crop subgroup 1D; turf; watercress; and wheat. 

The antimicrobial uses of azoxystrobin for mold control on indoor surfaces include material 

preservation in paints and coatings, rubber and plastics, textiles, paper and paperboard products 

and drywall, and as a mold spray inside residential areas including structural wood, subflooring, 

drywall and carpet.

Azoxystrobin may be applied to agricultural commodities using ground (groundboom and 

airblast), aerial, chemigation, and handheld equipment. Handheld application equipment is used 

inside/around residential areas. Seed treatment is expected to occur in commercial treatment 

facilities only. All registered labels require occupational handlers to wear baseline attire (long 

sleeved shirt, long pants, shoes/socks) and chemical resistant gloves. Some labels require 

additional personal protective equipment (PPE) such as protective eyewear, dust/mist respirators, 

 

1 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-proceduresresidential-pesticide
Page 5 of 64

coveralls, and aprons. Those EUPs requiring PPE beyond baseline attire and chemical resistant 

gloves are co-formulations with other active ingredients. The restricted entry intervals (REIs)

range from 4 hours to 24 hours; those labels requiring REIs longer than 12 hours are all coformulations with other active ingredients. 

Exposure Profile – Conventional Residential & Agricultural Uses

Based on the currently registered uses of azoxystrobin, the durations of exposure are expected to 

be both short- (1 to 30 days) and intermediate-term (1 to 6 months) for agricultural occupational 

handlers. Although there is potential for long-term exposures to re-entry workers because cut 

flowers may be grown year-round, long-term exposures were not assessed because the registered 

labels explicitly state concerns for resistance and outline approaches for integrated pest 

management strategies. Exposures in residential settings and from spray drift are expected to be 

short-term only. 

Exposure Profile – Antimicrobial Uses 

Based on the currently registered antimicrobial uses of azoxystrobin, the durations of exposure 

are expected to be intermediate- to long-term for the occupational incorporation of material 

preservatives into paints and short- to intermediate-term for occupational use of preserved 

materials in paints. The residential handler exposure duration is anticipated to be short-term for 

both the material preservation and mold spray uses. The residential post-application exposure 

duration is anticipated to be short-term only.

Hazard Characterization 

The azoxystrobin database is complete for risk assessment, with the exception of a subchronic 

inhalation toxicity study on technical azoxystrobin. In repeat-dose oral studies, the liver and 

bile ducts were consistently the target organs of azoxystrobin toxicity. Developmental effects 

were not seen in rabbit or rat developmental toxicity studies. In the rat reproduction study, 

offspring and parental effects (decreased body weight and increased adjusted liver weight) were 

observed at the same dose in both offspring and parental animals. Therefore, the azoxystrobin 

toxicity data show no increased susceptibility in the young. Because there were no effects seen 

in a route-specific subchronic dermal study in the rat, and there was no concern for 

developmental or reproductive effects, a dermal risk assessment is not applicable at this time. 

For episodic ingestion of azoxystrobin granules, the point of departure (POD) (level of concern; 

LOAEL = 200 mg/kg/day) was selected based on diarrhea at two-hours post dose at all dose 

levels tested. For assessing acute risk, EPA is retaining a Food Quality Protection Act (FQPA) 

safety factor (SF) of 3X to account for the use of a LOAEL from the acute neurotoxicity study 

to derive an acute reference dose. For short- and intermediate-term incidental oral exposures, 

the POD was based on decreased pup weights in both males and females. This LOAEL will be 

protective of effects seen in the developmental toxicity study and in the 90-day oral toxicity 

study. A 100-fold uncertainty factor (10X for interspecies extrapolation, and 10X for 

intraspecies extrapolation) will be applied to the short- and intermediate-term incidental oral 

risk assessments. Since there was no concern for susceptibility of offspring and effects on 

offspring viability in the in the developmental or reproductive studies, the FQPA SF was 

reduced from 10X to 1X. Since the previous assessment, a route-specific 28-day inhalation 

toxicity study with the SC formulation was submitted and reviewed, and now provides the basis 

for the inhalation POD for azoxystrobin. The POD is based on adverse histopathological 
Page 6 of 64

changes in the larynx (squamous metaplasia) and nasal cavity (metaplasia of the respiratory 

epithelium. The standard interspecies extrapolation UF is reduced from 10X to 3X due to the 

calculation of HECs accounting for pharmacokinetic (not pharmacodynamic) interspecies 

differences. For intraspecies variation, 10X is applied. An additional 10X is applied for a 

database uncertainty factor to account for the requirement for an inhalation toxicity study on the 

technical active ingredient (a.i.) because the available 28-day inhalation study was tested on 

only approximately 8% a.i., whereas most of the marketed products contained 30 - 50% a.i. 

Therefore, the LOC for inhalation exposures is a margin of exposure (MOE) less than 300 (3X 

for interspecies extrapolation, 10X for intraspecies variation, and 10X for database 

uncertainty/FQPA SF). 

Residential Exposure and Risk Assessment – Conventional Uses 

There is potential residential exposure from the existing conventional uses of azoxystrobin. 

Some of the residential handler inhalation risk estimates for the registered conventional uses of 

azoxystrobin are of concern (MOE < 300). However, the registered conventional residential uses 

of azoxystrobin do not result in any risks of concern for post-application incidental oral or 

inhalation exposures. 

Residential Exposure and Risk Assessment – Antimicrobial Uses 

There is potential residential exposure from the existing antimicrobial uses of azoxystrobin. The 

inhalation PODs have changed since the previous assessment. Therefore, the antimicrobial 

inhalation scenarios have been reevaluated to incorporate changes to the azoxystrobin toxicity 

database. Residential handler inhalation exposures were assessed for applying azoxystrobintreated paint and for applying mold spray. The MOEs are of concern (MOE < 300) for the mold 

spray scenario, and the airless sprayer and brush/roller painting scenarios for applying 

azoxystrobin treated paints.

There is the potential for residential post-application exposure to vinyl flooring made from 

azoxystrobin treated vinyl, contact with plastic toys manufactured from azoxystrobin treated 

plastic, and carpets treated with the azoxystrobin mold spray. Incidental oral MOEs for 

treated/impregnated vinyl flooring, treated plastic toys, and object-to-mouth exposures from 

treatments on hard surfaces and carpets were not of concern. Residential post-application 

inhalation MOEs were also not of concern for adults or children 1 to < 2 years old following 

surface directed mold sprays. 

Occupational Exposure – Conventional Agricultural uses 

Some occupational handler risk estimates resulted in inhalation MOEs of concern with baseline

PPE; some scenarios resulted in MOEs of concern using maximum levels of PPE or engineering 

controls for agricultural, post-harvest, and seed treatment uses (MOEs < 300). 

Because no dermal POD was selected for azoxystrobin, an occupational post-application 

exposure assessment was not completed. Post-application inhalation exposure following the 

planting of azoxystrobin-treated seeds is unlikely because sustained levels of contact with treated 

seed after placement in soil or other growing media is not expected; therefore post-application 

exposure is expected to be negligible and a quantitative post-application assessment was not 

required for the seed treatment uses of azoxystrobin. Based on the Agency's current practices, a 
Page 7 of 64

quantitative non-cancer occupational post-application inhalation exposure assessment was not 

performed for the agricultural uses azoxystrobin at this time. If new policies or procedures are 

put into place, the Agency may revisit the need for a quantitative occupational post-application 

inhalation exposure assessment for azoxystrobin. However, there is the potential for 

occupational post-application inhalation exposures in post-harvest treatment facilities. There are 

some occupational post-application inhalation risk estimates of concern for the registered postharvest uses of azoxystrobin at baseline and maximum PPE mitigation (MOE < 300). 

Occupational Exposure - Antimicrobial Uses

Occupational handler inhalation exposures were assessed for open pouring during paint 

preservation and for airless spray and brush/roller application of preserved paint and resulted in a 

risk estimate of concern (MOE < 300) at baseline. If a PF10 elastomeric half face respirator is 

worn, the MOE is increased to 300 and is no longer of concern. Application of preserved pain 

using an airless sprayer and brush/rollers result in risk estimates of concern (MOE < 300). These 

risks cannot be mitigated with respiratory protection because only the materials preservatives to 

preserve paints are EPA registered pesticide products; preserved paints themselves are not EPA 

registered pesticide products and thus do not have labels that could include PPE requirements. 

Human Studies Review

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 data, which include studies from 

PHED 1.1; the AHETF database; the AEATF database; ExpoSAC Policy 14 (SOPs for Seed 

Treatment); and the Residential SOPs (Treated Paints, Lawns/Turf, and Indoor Environments); 

are (1) subject to ethics review pursuant to 40 CFR 26, (2) have received that review, and (3) are 

compliant with applicable ethics requirements. For certain studies, the ethics review may have 

included review by the Human Studies Review Board. Descriptions of data sources, as well as 

guidance on their use, can be found at the Agency website2. 

2.0 Risk Assessment Conclusions and Recommendations

2.1 Summary of Risk Estimates

 As no systemic dermal toxicity was identified, occupational and residential dermal 

exposure/risk assessments were not conducted. 

 Residential handler inhalation risk estimates were of concern for some scenarios:

o Mixing/loading/applying liquids using a hose-end sprayer to turf, 

o Mixing/loading/applying liquids using a backpack sprayer to turf,

o Mixing/loading/applying dry flowable formulations using a manually 

pressurized handwand to turf, 

o Mixing/loading/applying a dry flowable formulation using a hose-end sprayer 

to turf, 

o Mixing/loading/applying dry flowable formulations using a backpack sprayer 

to turf, 

 

2 http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html
Page 8 of 64

o Hand dispersal of granules to gardens/trees, 

o Application of paint containing azoxystrobin with airless sprayers and brush 

rollers, and 

o Mixing/loading/applying azoxystrobin with a low pressure handwand indoors 

for mold spray treatment. 

 Some occupational inhalation handler and post-application risk estimates were 

of concern at baseline and require respiratory protection to mitigate risks. In some 

cases, standard respiratory protection measures/engineering controls do not appear to 

be successful in mitigating inhalation risk estimates of concern. These scenarios 

include: 

o Mixing/loading dry flowables for aerial, airblast, groundboom, and 

chemigation application to all registered crops at maximum registered 

application rates; 

o Mixing/loading granules for aerial application to sod; 

o Mixing/loading granules for tractor-drawn spreader applications to sod and 

golf course fairways, greens, and tees. 

o Mixing/loading liquids for aerial application to orchards/vineyards, sod, 

typical field crops, and high acreage field crops at maximum registered 

application rates; 

o Mixing/loading liquids for chemigation application to orchards/vineyards, 

sod, typical field crops, high acreage field crops; 

o Mixing/loading liquids for groundboom application to sod and high acreage 

field crops; 

o Applying sprays with airblast application equipment to nursery ornamentals 

and orchards/vineyards; 

o Applying sprays with groundboom application equipment to sod; golf course 

fairways, tees, and greens; typical field crops; and high acreage field crops; 

o Applying granules with aerial application equipment to sod; 

o Applying granules with a tractor-drawn spreader to sod, and golf course 

fairways, greens, and tees; 

o Flagging for aerial application to sod during liquid and granular applications; 

o Mixing/loading/applying dry flowable or liquid formulations with a backpack 

sprayer to orchard/vineyards, Christmas tree farms, and nursery ornamentals; 

o Mixing/loading/applying dry flowable or liquid formulations using a manually 

pressurized handwand to Christmas tree farms, nursery ornamentals, and 

landscaping; 

o Mixing/loading/applying dry flowable or liquid formulations using a 

mechanically pressurized handwand to orchard/vineyards, Christmas tree 

farms, nursery ornamentals, golf courses, landscaping, and typical field crops; 

o Mixing/loading/applying liquids with a manually pressurized handwand to 

greenhouse ornamentals; 

o Mixing/loading/applying liquids with a mechanically pressurized handwand to 

orchards/vineyards, Christmas tree farms, nursery ornamentals, greenhouse 

ornamentals, landscaping, and typical field crops; 
Page 9 of 64

o Loading/applying granule formulations with a rotary spreader to golf courses; 

o Mixing/loading for post-harvest treatments in a closed system to citrus; 

o Mixing/loading dry flowable formulations in an automated system for postharvest treatment of bananas, 

o Mixing/loading liquids in an automated system for post-harvest treatment fo 

citrus; 

o Applying direct post-harvest sprays using a mechanically pressurized handgun 

to citrus and bananas; 

o Loading/applying, sewing, bagging, and multiple activities for numerous 

liquid seed treatment uses of azoxystrobin; 

o Planting treated barley, legume vegetable, peanut, potato, triticale, tuberous 

and corm vegetable, turf, and wheat seeds with liquid formulations of 

azoxystrobin; 

o Loading/applying, sewing, bagging, multiple activities for dust seed treatment 

applications to peanuts; 

o Planted peanut seeds treated with dust formulations; 

o Loading/applying, sewing, bagging, and multiple activities for cotton dry 

flowable seed treatment uses of azoxystrobin; 

o Adding azoxystrobin to pain during manufacturing; and

o Sorting and packing following post-harvest treatment of citrus and bananas.

2.2 Label Recommendations from Occupational Assessment 

Labels vary considerably with respect to requirements for work attire and PPE. For example, 

some labels do not specify any requirements for work attire, while others require respirators and 

coveralls over long-sleeve shirt and long pants. Like work attire and PPE, REIs also vary 

considerably across labels (e.g., 4 hours versus 48 hours). Thus, label corrections/revisions 

should be consistently made to default to end-use product and/or technical grade active 

ingredient acute (ocular, dermal, oral, and inhalation) toxicity requirements. Additional PPE, 

such as respiratory protection, beyond end-use product acute toxicity requirements, should be 

considered as described in the context of any risks of concern identified in this assessment.

It is recommended that the material preservation labels be amended to include the use of 

respiratory protection for open pouring.

2.3 Label Recommendations from Residential Assessment

Some azoxystrobin products are intended for use by residential applicators on home lawns or 

residential areas but require certain clothing and/or PPE to be worn. Thus, standard assumptions 

for residential/consumer applicator specific assessments, such as wearing shorts and a t-shirt 

without PPE like chemical-resistant gloves or respirators, would represent non-compliance with 

currently registered products. If products containing azoxystrobin are meant to be marketed 

towards and applied by homeowners on residential turf, ornamentals, and in homes, HED 
Page 10 of 64

recommends that the label requirements for clothing and/or PPE be reevaluated or separate 

consumer-specific labels be developed. 

Note to PRD: It is recommended that the EPA registered label Reg. No. 100-1093 be split into 

two separate labels: one label for conventional uses, and one label for antimicrobial uses that 

would be regulated by AD. 

3.0 Hazard Characterization

Updates have been made to the azoxystrobin endpoints and PODs since the previous risk 

assessment (K. Rury, D418012 and D423847, 12/17/2014). 

Acute Toxicity

Azoxystrobin exhibits low acute mammalian toxicity via oral, dermal, and inhalation routes of 

exposure (Category III or IV for acute lethality and irritation studies) and is not a dermal irritant 

or sensitizer.

Table 3.1. Acute Toxicity Data on Technical Azoxystrobin. 

Guideline

No. Study Type MRID # Results Toxicity Category

870.1100 Acute Oral - Rat 43678122 LD50 > 5000 mg/kg (Limit Test) in Males & 

Females IV

870.1200 Acute Dermal -

Rat 43678124 LD50 > 2000 mg/kg (Limit Test) in Males & Females III

870.1300 Acute Inhalation -

Rat 43678126

LC50 Males = 0.962 mg/L (95% C.I. = 0.674)

Females = 0.698 mg/L (95% C.I. = 0.509, 2.425)

The combined LC50 was not calculated

due to mortality pattern

III

870.2400 Primary Eye 

Irritation - Rabbit 43678128

Slight to moderate erythema and slight chemosis in 

all rabbits within one hour, but effects resolved 

within 48 hours of treatment.

III

870.2500 Primary Skin 

Irritation - Rabbit 43678130

Very slight erythema and edema that persisted for 

three days on one rabbit and for one hour on 

another.

IV

870.2600

Dermal 

Sensitization -

Guinea Pig

43678132 No erythema or edema were found 38 or 48 hrs 

after challenge with test material.

Not a 

dermal 

sensitizer

Toxicological PODs Used for Risk Assessment

The azoxystrobin database is complete and adequate for risk assessment. In repeat-dose oral 

studies, the liver and bile ducts were consistently the target organs of azoxystrobin toxicity. 

Developmental effects were not seen in rabbit or rat developmental toxicity studies. In the rat 

reproduction study, offspring and parental effects (decreased body weight and increased adjusted 

liver weight) were observed at the same dose in both offspring and parental animals. Therefore, 

the azoxystrobin toxicity data show no increased susceptibility in the young. 

In a 21-day repeated dose dermal study in the rat, neither dermal nor systemic toxicity was seen 

at the limit dose (1,000 mg/kg/day). Furthermore, there was no concern for developmental or 
Page 11 of 64

reproductive effects. Therefore, a hazard was not identified for short- and intermediate-term 

dermal exposure scenarios, and a dermal risk assessment is not applicable at this time. 

For short- and intermediate-term incidental oral exposures the POD (i.e., no observable adverse 

effect level (NOAEL) = 35 mg/kg/day) included the results of the 2-generation reproduction 

study in rats, the developmental toxicity study in rats, and the 90-day oral toxicity study in rats. 

The POD is based on decreased pup weights in both males and females at the lowest observable 

adverse effect level (LOAEL) of 165 mg/kg/day. This LOAEL is protective of effects seen in 

the developmental toxicity study and in the 90-day oral toxicity study. A 100-fold uncertainty 

factor (UF) [10X for interspecies extrapolation, 10X for intraspecies extrapolation, and 1X for

the Food Quality Protection Act (FQPA) Safety Factor (SF)] is applied to short-term incidental 

oral risk assessments.

For short-, intermediate-, and long-term inhalation exposure assessment, the POD (no observed 

adverse effect level; NOAEL = 3.8 μg/L) was selected based on a route-specific inhalation 

toxicity study in rats with the soluble concentrate (SC) formulation of azoxystrobin. The 

LOAEL of 11.2 μg/L was based on adverse microscopic changes seen in the nasal cavity and the 

larynx. Human equivalent concentrations (HECs) for residential and occupational scenarios 

were derived using the NOAEL and the regional deposited-dose ratio (RDDR). Subsequently, 

human-equivalent doses (HEDs) were calculated from the HECs for residential and occupational 

handler scenarios. The standard interspecies extrapolation UF is reduced from 10X to 3X due to 

the calculation of HECs accounting for pharmacokinetic (not pharmacodynamic) interspecies 

differences. The intraspecies variation UF of 10X is retained. An additional 10X is applied for a 

database UF because the available 28-day inhalation toxicity study was not conducted using 

technical grade active ingredient. Consequently, the LOC for inhalation exposures is an MOE 

less than 300 [3X for interspecies extrapolation, 10X for intraspecies variation, and 10X for 

database uncertainty or in the case of residential exposures, FQPA SF].

For episodic ingestion of azoxystrobin granules, the POD (LOAEL = 200 mg/kg/day) was 

selected based on diarrhea at two-hours post dose at all dose levels tested. For assessing acute 

risk, EPA is retaining an FQPA factor of 3X to account for the use of a LOAEL from the acute 

neurotoxicity study to derive an acute reference dose. The Agency believes that a 3X FQPA SF 

(as opposed to a 10X) will be adequate to extrapolate a NOAEL in assessing acute risk based on 

the following considerations: (1) The LOAEL is based on a transient effect (diarrhea in rats) 

expected to be relatively insignificant in nature. This effect is also seen in other chemicals of the 

same class. (2) The diarrhea was only seen in studies using gavage dosing in the rat, but not in 

studies using repeat dosing through dietary administration in rats or mice, and not through 

gavage dosing in rabbits. (3) The very high dose level needed to reach the acute oral lethal dose 

(LD) 50 (>5000 mg/kg), and the overall low toxicity of azoxystrobin. Consequently, the LOC for 

acute episodic incidental ingestion is an MOE less than 300 [10X for interspecies extrapolation, 

10X for intraspecies variation, and 3X for LOAEL to NOAEL extrapolation].

Azoxystrobin is characterized as "not likely" to be a human carcinogen. The FQPA SF has been 

reduced to 1X for all non-acute exposure durations. Azoxystrobin exhibits low acute 

mammalian toxicity via oral, dermal, and inhalation routes of exposure (Category III or IV for 

acute lethality and irritation studies) and is not a dermal irritant or sensitizer.
Page 12 of 64

Table 3.2. Summary of Toxicological Doses and Endpoints for Azoxystrobin for Use in Non-Occupational

Human Health Risk Assessments.1

Exposure/

Scenario

Point of Departure

Uncertainty/

FQPA 

Safety 

Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological 

Effects

Episodic Granule 

Ingestion

(Children 1 to < 2 

years old)

LOAEL = 200 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 

3X

Residential 

LOC for MOE 

= 300

Acute Neurotoxicity - Rat. 

LOAEL = 200 mg/kg/day based 

on diarrhea at two-hours post 

dose at all dose levels tested.

Incidental Oral 

Short-Term (1-30 

days) & 

Intermediate-term (1-

6 months)

NOAEL = 35 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 

1X

Residential 

LOC for MOE 

= 100

2-generation reproduction study 

–rats

LOAEL = 165 mg/kg/day based 

on decreased pup weights in 

both males and females (↓8-

21%).

Dermal

(All Durations) No hazard was identified for this exposure scenario.

21-Day Repeated Dose Dermal 

Study – Rat. No dermal or 

systemic toxicity was seen at the 

limit dose (1,000 mg/kg/day).

Inhalation

2

(All Durations)

Rat inhalation

NOAEL=3.8 μg/L

UFA=3

UFH=10

UFDB= FQPA 

SF = 10X+

LOC = 300

28-Day inhalation toxicity study 

in rats on SC formulation+

LOAEL = 12.2 μg/L based on 

adverse histopathological 

changes in the larynx (squamous 

metaplasia) and nasal cavity 

(metaplasia of the respiratory 

epithelium.). There was an 

increase severity with increases 

in the test concentrations.

Conventional 

Residential Uses:

HEC3 = 0.688 

mg/cubic meter

HED4 =0.02 

mg/kg/day (16.7 

L/min)

Antimicrobial 

Residential 

Uses++:

HEC3 = 0.516 

mg/cubic meter

HED4 =

0.059 mg/kg/day 

(16.7 L/min)

Cancer

(oral, dermal, 

inhalation)

Azoxystrobin is classified as "Not Likely" to be carcinogenic to humans.

1. Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the 

beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed 

adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = extrapolation from animal to human 

(interspecies). UFH = 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. MOE = margin of exposure. LOC = level of 

concern. N/A = not applicable.

2. To protect for the body weight decreases seen in the pups, a 69 kg body weight was used for estimating short- and intermediate-term 

inhalation doses because the pup body weight decrease also influenced by the maternal health. 

3. HEC = rat NOAEL*(daily duration adjustment)*weekly daily duration adjustment *RDDR*

4. HED = HEC*human specific conversion factor*daily duration
Page 13 of 64

+: An inhalation study on active ingredient (a.i.) is recommended. This safety factor is to account for lack of a study with the a.i.

++AD assumes that the exposure duration for residential painting and mold spraying is 8 hours per day (ventilation rate = 16.7 LPM).

Table 3.3. Summary of Toxicological Doses and Endpoints for Azoxystrobin for Use in Occupational Human 

Health Risk Assessments.1

Exposure/

Scenario Point of Departure

Uncertainty/

FQPA Safety 

Factors

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Dermal

(All 

Durations)

No hazard was identified for this exposure scenario.

21-Day Repeated Dose Dermal 

Study – Rat. No dermal or 

systemic toxicity was seen at the 

limit dose (1,000 mg/kg/day).

Inhalation2

Short-Term 

(1-30 days) &

IntermediateTerm

(1-6 months)

Rat inhalation

NOAEL=3.8 μg/L

UFA=3

UFH=10

UFDB=10+

LOC = 300

28-Day inhalation toxicity study in 

rats on SC formulation

LOAEL = 12.2 μg/L based on 

adverse histopathological changes 

in the larynx (squamous 

metaplasia) and nasal cavity 

(metaplasia of the respiratory 

epithelium.). There was an 

increase severity with increases in 

the test concentrations.

Occupational handler

HEC3 = 0.516 

mg/cubic meter

HED4(mg/kg/day):

0.029 (8.3 L/min)++

0.059 (16.7 L/min) ++

0.103 (29 L/min) ++

Cancer

(oral, dermal, 

inhalation)

Azoxystrobin is classified as "Not Likely" to be carcinogenic to humans.

1. Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the 

beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no observed 

adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = extrapolation from animal to human 

(interspecies). UFH = 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. MOE = margin of exposure. LOC = level of 

concern. N/A = not applicable.

2. To protect for the body weight decreases seen in the pups, a 69 kg body weight was used for estimating short- and intermediate-term inhalation 

doses because the pup body weight decrease also influenced by the maternal health. 

3. HEC = rat NOAEL*(daily duration adjustment)*weekly daily duration adjustment *RDDR*

4. HED = HEC*human specific conversion factor*daily duration

+: An inhalation study on active ingredient (a.i.) is recommended. This safety factor is to account for lack of a study with the a.i.

++: Three ventilation rates corresponding to three HEDs used for assessing occupational inhalation exposures.

Absorption

The inhalation POD is based on a route-specific inhalation toxicity study; therefore, an inhalation 

absorption factor is not applicable. A dermal absorption factor is not applicable because a 

dermal hazard was not identified for azoxystrobin. 

Body Weight

The standard body weights for adults (80 kg) and children (1 to < 2 years old, 11 kg; 6 to < 11 

years old, 32 kg; and 11 to < 16 years old, 57 kg) were used for all exposure scenarios covered in 

this risk assessment since the endpoints selected were not developmental and/or fetal effects.

4.0 Use Profile 

Azoxystrobin is currently formulated as liquid, dry flowable, granule, and dust end-use products 

(EUPs) containing between 0.31% and 50% ai. Azoxystrobin is registered for agricultural use on 

numerous fruit and vegetable crops growing in both fields and greenhouses. Azoxystrobin is 
Page 14 of 64

also registered as a post-harvest treatment for use on bananas, plantains, citrus, and tuberous and 

corm vegetables. It may also be used on golf course turf, lawns, sports fields, ornamentals, 

conifers, roses, cut flowers, interior plantscapes, and sod. Seed treatment uses of azoxystrobin 

include the following commodities: barley; Brassica (cole) leafy vegetables, crop group 5; bulb 

vegetables, crop group 3; canola; corn (field, pop, sweet); cotton; cucurbit vegetables, crop group 

9; eggplant; leafy vegetables, crop group 4; leaves of root and tuber vegetables, crop group 2; 

legume vegetables (succulent or dried), crop group 6; okra, peanut; peppers; potato; rice; root 

vegetables, crop subgroup 1A; soybean; sunflower; tomato; triticale; tuberous and corm 

vegetables (except potato), crop subgroup 1D; turf; watercress; and wheat. 

The antimicrobial uses of azoxystrobin for mold control on indoor surfaces include material 

preservation in paints and coatings, rubber and plastics, textiles, paper and paperboard products 

and drywall, and as a mold spray inside residential areas including structural wood, subflooring, 

drywall and carpet.

Table 4.1. Summary of Directions for the Agricultural Uses of Azoxystrobin1.

Formulation

Applic. 

Timing, Type, 

and Equip.

Use Site Applic. Rate 

(lb ai/A)

Max. Seasonal 

Applic. Rate 

(lb ai/A)

RTI (days)2

Liquid Ground, Aerial, 

Chemigation

Almonds; Artichoke, globe; 

Asparagus; Canberries; Brassica

Head and Stem Subgroup; Bulb 

vegetables; Celery; Citrus; 

Cranberry; Cucurbits; Grapes 13-

07F; Leafy vegetables; Legume 

vegetables; Pistachios; Soybean; 

Stone fruit; Tropical fruit; Wasabi; 

Watercress

0.25 1.5

Bulb vegetables, Cucurbits, 

Leafy vegetables, Vegetables 

root and tuber tuberous and 

corm = >5 

Soybean = NS 

Tropical fruit = 10-14 

All other crops = >7

Bananas/plantains 0.135 1.08 12-14 

Cereal grains (Barley, Oats, Rye); 

Wheat; Triticale 0.2 0.4 NA (max 2 applications)

Bushberry Subgroup 13-07B;

Brassica leafy greens; 0.25 0.75 7-14 

Low growing berries; Fruiting 

vegetables; 0.25 1.0 >7

Canola 0.25 0.45

Make one application at early 

bud, one at 45 days pre 

harvest, and one at 30 days 

pre harvest

Carrots, Potatoes; Vegetables, 

leaves of root and tuber group and 

root subgroup; Vegetables, tuberous 

and corm group

0.33 2.0 7-14

Liquid

Ground, Aerial, 

Chemigation

Chickpeas 0.18 N/S NS

Christmas Trees; Corn (field, pop, 

sweet seed); Conifers; Roses; 0.25 2.0 >7

Cotton 0.15 0.4 14-21

Air and ground Filberts 0.2 N/S NS

Ground, Aerial, 

Chemigation Grasses grown for seed; Mint 0.25 0.8 Grasses = 10-14 Mint = 7-10 

Ground only Herbs and spices 0.25 1.5 7
Page 15 of 64

Table 4.1. Summary of Directions for the Agricultural Uses of Azoxystrobin1.

Formulation

Applic. 

Timing, Type, 

and Equip.

Use Site Applic. Rate 

(lb ai/A)

Max. Seasonal 

Applic. Rate 

(lb ai/A)

RTI (days)2

Ground, Aerial, 

Chemigation

Non-grass animal feeds, forage, 

fodder, straw, and hay 0.25 0.25 NS

Oilseeds, Crop Group 20 0.25 0.4 NS

Onion (green, dry, and bunching) 0.23 N/S N/S

Peanuts 0.4 0.8 NS (ground directed)

10-14 (foliar)

Pecans; Tree nuts; 0.20 1.2 7-21

Rice; Wild rice 0.3 0.7 7-14

Sorghum 0.25 0.75 NS

Sugarcane 0.2 0.8 14-28

Tobacco 0.2 0.52 7-14

Tomato, subgroup 8-10A 0.1 0.6 7-21

Post-harvest bananas/plantains 0.00034 lb 

ai/gal NA NA

Post-harvest citrus 0.148 lb 

ai/gal NA NA

Post-harvest tuberous and corm 

vegetables

0.00000049 

lb ai/lb NA NA

Golf course turf; Lawns; Sports 

Fields 0.99 NS >10

Ornamentals 0.24 NS 7-14

Cut flowers 0.06 NS >7

Greenhouse ornamentals 0.26 NS >7

Greenhouse vegetables 0.18 NS >7

Greenhouse tomatoes 0.10 NS 7-10

Liquid

Commercial 

Seed Treatment 

Equipment

Barley, Bell Pepper, Brassica, Bulb 

Vegetables, Corn (field, pop, 

sweet), Cotton, Cucurbits, 

Eggplant, Leafy Vegetables, 

Legume Vegetables, Non-Bell 

Pepper, Okra, Ornamental Bulbs, 

Ornamental Seed, Peanuts, Potato, 

Root Vegetables, Sunflower, 

Sorghum, Tomato, Triticale, 

Tuberous and Corm Vegetables, 

Turf, Watercress, Wheat 

0.000244 (lb 

ai/lb seed) NA NA

Rice 0.000070 (lb 

ai/lb seed) NA NA

Soybean 0.00003 (lb 

ai/lb seed) NA NA

Cotton 0.00018 (lb 

ai/lb seed) NA NA

Dry Flowable

Ground, Aerial, 

Chemigation, 

Handheld (if 

applicable)

Almonds; Artichoke, globe; 

Asparagus; Caneberries; Brassica

Head and Stem Subgroup; Bulb 

vegetables; Celery; Legume 

Vegetables, dry and succulent; 

0.25 1.5

Bulb vegetables, cucurbits, 

leafy vegetables, = >5 

Grapes, Tropical fruit = >10 

Soybeans = NS

All other crops = >7
Page 16 of 64

Table 4.1. Summary of Directions for the Agricultural Uses of Azoxystrobin1.

Formulation

Applic. 

Timing, Type, 

and Equip.

Use Site Applic. Rate 

(lb ai/A)

Max. Seasonal 

Applic. Rate 

(lb ai/A)

RTI (days)2

Citrus; Cranberry; Cucurbits; 

Grapes 13-07F; Leafy Vegetables; 

Pistachios; Soybean; Stone fruit; 

Tropical Fruit; Watercress

Bananas/Plantains 0.135 1.08 12-14

Dry Flowable

Cereal Grains; Wheat; Triticale 0.2 0.4 NS

Bushberry Subgroup 13-07B; 

Brassica leafy greens; Mint 0.25 0.75 >7

Strawberry; Fruiting Vegetables 

except tomatoes 0.25 1.00 >7

Canola 0.125 0.86 NS

Carrots 0.33 0.48 7-14

Christmas trees; Corn (field, pop, 

seed, sweet); Conifers; Roses 0.25 2.00 >7

Cotton 0.15 NA One application per season

Dry Flowable

Ground, Aerial, 

Chemigation Grasses grown for seed 0.25 0.8 10-14

Ground only Herbs and Spices 0.25 1.5 7

Ground, 

Chemigation Wasabi 0.25 NS NS

Ground, Aerial, 

Chemigation

Oilseeds crop group 20 0.25 0.45 NS

Peanuts – soilborne 0.4 8.0 NS

Peanuts – foliar 0.3 10-14

Potatoes; Vegetables, leaves of root 

and tuber; Vegetables, tuberous and 

corm

0.33 2.0 >5

Rice 0.3 0.7 7-14

Tomatoes 0.1 0.8 >5

Tree Nuts 0.2 1.2 7-21

Turf 0.95 NS NS

Ornamentals 0.04 0.0125 NS

Post-Harvest 

Spray 

Equipment

Post-Harvest Bananas/Plantains 400 (ppm) NA NA

Seed Treatment 

Equipment Cotton 0.0002 lb ai/lb seed NA NA

Granules

Ground, Aerial, 

Handheld Turf, Lawn and Golf course 0.95 5.0 14-28

Dust Seed Treatment 

Equipment Peanuts 0.00008 lb ai/lb seed NA NA

1 NS = Not specified, NA = Not applicable

2 RTIs are based on the following representative labels: 

a. Liquid: EPA Reg. No. 89442-21 

b. Liquid greenhouse: EPA Reg. No. 100-1506 

c. Dry Flowable: EPA Reg. No. 100-1093

d. Granules: EPA Reg. No. 100-1275
Page 17 of 64

Table 4.2. Azoxystrobin Antimicrobial Uses. 

Use Application Rate Application 

Method Comment

Material Preservation Uses

Ceiling Tiles 0.048 to 0.33% ai in wet 

slurry Open Pour Liquid N/A

Latex Caulks, Sealants, Adhesives 

and Binders 0.015 to 0.305% ai Open Pour Liquid N/A

Textiles, Fabrics, Canvas and 

Cordage 0.015 to 0.23% ai Open Pour Liquid Not for apparel

Rubber and Plastic Products 0.076 to 0.23% ai Open Pour Liquid

Not for use in food and 

beverage containers including 

plastic piping carrying water or 

beverages and piping for food 

processing equipment

Paints, Stains and Coatings 0.029 to 0.305% ai Open Pour Liquid N/A

Paper, Wallboard and Paperboard 

Products

48 to 190 ppm ai in dry 

paper

Open Pour Liquid N/A

Residential and Public Access Premises

Indoor Residential Mold Spray 0.0078 lb ai per gallon Handwand 

Sprayer 100-1093

1 Not for use in food and beverage containers including plastic piping carrying water or beverages and piping for food processing 

equipment

5.0 Residential Exposure and Risk Estimates

There is potential residential exposure from the existing conventional and antimicrobial uses of 

azoxystrobin. All existing conventional residential uses were previously reassessed to reflect 

HED’s 2012 Residential SOPs3(K. Rury, DP394287, 03/30/2012; K. Rury, D418012 and 

D423847, 12/17/2014). However, the inhalation PODs have changed since the previous 

assessment. Therefore, the conventional and antimicrobial inhalation scenarios have been 

reevaluated to incorporate changes to the azoxystrobin toxicity database. 

5.1 Residential Handler Exposure/Risk Estimates

HED uses the term “handlers” to describe those individuals who are involved in the pesticide 

application process. HED believes that there are distinct tasks related to applications and that 

exposures can vary depending on the specifics of each task. Residential handlers are addressed 

somewhat differently by HED as homeowners are assumed to complete all elements of an 

application without use of any protective equipment.

The quantitative exposure/risk assessment developed for residential handlers is based on the 

scenarios listed in Table 5.1.1. 

Conventional Uses

Residential Handler Exposure Data and Assumptions –

 

3 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-proceduresresidential-pesticide
Page 18 of 64

A series of assumptions and exposure factors served as the basis for completing the residential 

handler risk assessments. Each assumption and factor is detailed below.

Application Rate: The registered application rates of azoxystrobin quantitative exposure/risk 

assessment developed for residential handlers is based on the scenarios listed in Table 4.1. 

Unit Exposures and Area Treated or Amount Handled: Unit exposure values and estimates for 

area treated or amount handled were taken from HED’s 2012 Residential SOPs4. 

Exposure Duration: Residential handler exposure is expected to be short-term in duration. 

Intermediate-term exposures are not likely because of the intermittent nature of applications by 

homeowners.

Residential Handler Non-Cancer Exposure and Risk Estimate Equations- Conventional Uses

The algorithms used to estimate exposure and dose for residential handlers can be found in 

Appendix A and the 2012 Residential SOPs5.

Summary of Residential Handler Non-Cancer Exposure and Risk Estimates – Conventional Uses

For residential handlers, exposures from application to turf were not combined with exposures 

from treating gardens/trees because concurrent use of separate pesticide products that contain the 

same active ingredient to treat the same or different pests does not typically occur. Additionally, 

combining exposures to these uses is not considered appropriate in light of the already 

conservative assumptions inherent in the assessment. For example, when assessing individual 

short-term residential handler exposure scenarios, EPA assumes exposure occurs to the highest 

registered application rate, day after day, for the same amount of time each day, for up to 30 days 

for short-term exposures. Exposure estimates are then compared to points of departure that are 

typically based on weeks of dosing in test animals. Therefore, although the same products allow 

treatment of gardens/trees and turf, these exposures were not combined for residential handlers. 

Some of the residential handler inhalation risk estimates for the registered uses of azoxystrobin 

are of concern. The individual scenarios of concern include: 

 Mixing/loading/applying liquids using a hose-end sprayer to turf, 

 Mixing/loading/applying liquids using a backpack sprayer to turf, 

 Mixing/loading/applying dry flowable formulations using a manually pressurized 

handwand to turf, 

 Mixing/loading/applying a dry flowable formulation using a hose-end sprayer to turf, 

and 

 Mixing/loading/applying dry flowable formulations using a backpack sprayer to turf.

 Hand dispersal of granules to gardens/trees.

All other scenarios are not of concern for the registered conventional uses of azoxystrobin in 

residential areas. 

 

4 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-proceduresresidential-pesticide

5 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-proceduresresidential-pesticide
Page 19 of 64

Table 5.1.1. Residential Handler Non-cancer Exposure and Risk Estimates for Azoxystrobin.

Exposure Scenario Formulation

Inhalation Unit 

Exposure 

(mg/lb ai)

Maximum 

Application Rate1

Area Treated 

or Amount 

Handled 

Daily2

Inhalation

Dose 

(mg/kg/day)3

MOE

(LOC = 300)4

Mixer/Loader/Applicator

Manually Pressurized Handwand 

to Gardens/Trees

Liquid

0.018 0.0013 lb ai/gal 5 gal 0.0000015 14,000

Manually Pressurized Handwand 

to Turf 0.018 0.01 lb ai/gal 5 gal 0.000011 1,800

Hose-end Sprayer to 

Gardens/Trees 0.0014 0.0013 lb ai/gal 11 gal 0.00000025 80,000

Hose-end Sprayer to Turf 0.022 0.99 lb ai/A 0.5 acres 0.00014 150

Backpack Sprayer to 

Gardens/Trees 0.14 0.0013 lb ai/gal 5 gal 0.000011 1,800

Backpack Sprayer to Turf 0.14 0.01 lb ai/gal 5 gal 0.000088 230

Sprinkler Can to Gardens/Trees 0.0014 0.0013 lb ai/gal 5 gal 0.00000011 180,000

Sprinkler Can to Turf 0.022 0.000013 lb ai/ft2 1000 ft2 0.0000036 5,600

Manually Pressurized Handwand 

to Gardens/Trees

Dry Flowable

1.1 0.000125 lb ai/gal 5 gal 0.0000086 2,300

Manually Pressurized Handwand 

to Turf 1.1 0.119 lb ai/gal 5 gal 0.0082 2.4

Hose-end Sprayer to 

Gardens/Trees 0.0014 0.000125 lb ai/gal 11 gal 0.000000024 830,000

Hose-end Sprayer to Turf 0.022 0.95 lb ai/A 0.5 acres 0.00013 150

Backpack Sprayer to 

Gardens/Trees 1.1 0.000125 lb ai/gal 5 gal 0.0000086 2,300

Backpack Sprayer to Turf 1.1 0.119 lb ai/gal 5 gal 0.0082 2.4

Sprinkler Can to Gardens/Trees 0.0014 0.000125 lb ai/gal 5 gal 0.000010 1,900

Sprinkler Can to Turf 0.022 0.0000218 lb ai/ft2 1000 ft2 0.0000060 3,300

Belly Grinder to Turf

Granules

0.039

0.0000218 lb ai/ft2

1200 ft2 0.000013 1,600

Spoon around Gardens/Trees 0.087 1200 ft2 0.000028 700

Spoon to Turf 0.087 100 ft2 0.0000024 8,400

Cup around Gardens/Trees 0.013 1200 ft2 0.000043 4,700

Cup to Turf 0.013 100 ft2 0.00000035 56,000

Hand Dispersal around 

Gardens/Trees 0.38 1200 ft2 0.00012 160

Hand Dispersal to Turf 0.38 100 ft2 0.000010 1,900

Shaker Can around 

Gardens/Trees 0.013 1200 ft2 0.0000043 4,700

Shaker Can to Turf 0.013 100 ft2 0.00000035 56,000

1 Based on registered azoxystrobin products. Shaded MOEs indicated risk estimates of concern (MOE < 300). 

2 Based on HED’s 2012 Residential SOPs (http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standardoperating-procedures-residential-pesticide).

3 Inhalation Dose = Inhalation Unit Exposure (mg/lb ai) × Application Rate (lb ai/acre, gal, or ft2) × Area Treated or Amount 

Handled (A/day, gallons/day, or ft2/day) ÷ BW (80 kg).

4 Inhalation MOE = Inhalation HED (0.02 mg/kg/day) ÷ Inhalation Dose (mg/kg/day). LOC = 300. Shaded MOEs indicate 

risks of concern (LOC < 300). 
Page 20 of 64

Antimicrobial Uses

Residential Handler Exposure –– Treated Paint

All three of the antimicrobial end use products that are used for material preservation are added 

to paints. There is potential for residential handler exposure during the application of paints 

treated with azoxystrobin as a preservative. The exposure duration is assumed to be short term 

because it is likely that a residential painter would apply paints for a few days at a time. 

The following assumptions were used:

 The use rate is 0.31% a.i. by weight. 

 The amount of paint handled per day is 2 gallons for brush/roller applications and 15 gallons for airless 

sprayer applications. These are standard AD and HED assumptions.

 The body weight of an adult handler is 80 kg.

 The daily task duration is 8 hours.

The MOEs for residential handlers of azoxystrobin preserved paints are summarized in Table 

5.1.2. The MOEs are less than the LOC of 300 for both the airless sprayer and brush/roller 

scenarios, which means that the risks are of concern. These risks cannot be mitigated with 

respiratory protection because only the materials preservatives to preserve paints are EPA 

registered pesticide products; preserved paints themselves are not EPA registered pesticide 

products and thus do not have labels that could include PPE requirements. 

Residential Handler Exposure– Antimicrobial Mold Spray

There is one label product (EPA Reg. No. 100-1093) registered for indoor residential mold spray 

use. The label indicates that the product can only be used by residential applicators as a 

preventative treatment on up to 800 square feet and for remediation of areas of 10 square feet or 

less. This product is not for use by professional or commercial applicators. There is the 

potential for residential handler inhalation exposure during mold remediation treatments that are 

applied as a spray to wood, drywall, carpets, and non-food hard non-porous surfaces. 

The following assumptions were used:

 The application rate is 2.6 ounces of product per ten gallons of water. This rate is from page 84 of label 

100-1093. 

 The amount of spray applied by low pressure handwand sprayer is 10 gallons per day based on the label 

Table 5.1.2. Azoxystrobin Residential Handler Inhalation Exposure and Risk Estimates for Preserved Paint.

Scenario Application 

Rate1

Amount Paint 

Applied (lb/day)2

Amount ai 

Handled 

(lb/day)

Unit Exposure3

(mg/lb ai)

Daily Dose4

(mg/kg/day)

Inhalation 

MOE5

(LOC =300)

Application of Paint Containing Azoxystrobin

Airless sprayer 

0.31% ai by wt

150 

(15 gal x 10 

lb/gal)

0.47 0.56 0.0033 18

Brush/Roller 20

(2 gal x 10 lb/gal)

0.047 0.20 0.00012 170

1 Based upon maximum rate listed on label #39967-86. 

2 HED Standard Operating Procedures (SOPs) for Residential Exposure Assessment (October 22, 2012).

3 HED Occupational Pesticide Handler Unit Exposure Surrogate Reference Table (March, 2013).

4 Daily Dose = [Amount ai Handled (lb) * Unit Exposure (mg/lb)] ÷ Body Weight (80 kg).

5 MOE = HED (0.059 mg/kg/day for an 8 hour exposure at 16.7 liters/minute) ÷ Daily Dose (mg/kg/day). Shaded MOEs represent risk estimates of 

concern (MOE < 300). 
Page 21 of 64

directions above for the use dilution and the label recommendation to “Prepare no more mixture than is 

necessary for immediate use.

 The task duration is eight hours per day given the amount of spray applied.

 The body weight of an adult handler is 80 kg.

The unit exposures, application rates and amounts of products applied per day were used to 

calculate the MOE as shown in Table 5.1.3. The MOE is less than 300 and the risk is of concern.

5.2 Residential Post-application Exposure/Risk Estimates

5.2.1 Residential Post-Application Exposure/Risk Estimates – Conventional Uses 

There is the potential for post-application exposure for individuals exposed as a result of being in 

an environment that has been previously treated with azoxystrobin. The quantitative 

exposure/risk assessment for residential post-application exposures has been updated here for the 

purposes of the aggregate risk assessment because the inhalation POD has changed since the 

previous full assessment of all the existing residential uses (K. Rury, D394287, 03/30/2012). 

The quantitative exposure/risk assessment for residential post-application exposures is based on 

the scenarios listed in Table 5.2.1. The lifestages selected for each post-application scenario are 

based on an analysis provided as an Appendix in the 2012 Residential SOPs6. While not the only 

lifestage potentially exposed for these post-application scenarios, the lifestage that is included in 

the quantitative assessment is health protective for the exposures and risk estimates for any other 

potentially exposed lifestage. There was no dermal hazard identified for azoxystrobin; therefore 

only incidental oral and inhalation post-application exposures were assessed for the residential 

uses of azoxystrobin.

Residential Post-application Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the residential 

post-application risk assessment. Each assumption and factor is detailed in the 2012 Residential 

SOPs6.

Application Rate: The registered application rates of azoxystrobin on treated turf, ornamentals 

and golf courses are listed in Table 4.1. 

 

6 Available: http://www2.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-proceduresresidential-pesticide

Table 5.1.3. Azoxystrobin Residential Handler Inhalation MOEs for Mold Spray Treatment.

Scenario

Application 

Rate1

(% a.i.)

Amount Product 

Applied per 

Day2

Amount Ai 

Handled3

(lb/day)

Unit 

Exposure4

(mg/lb ai)

Daily Dose5

(mg/kg/day)

Inhalation 

MOE

(LOC = 300)6

Low Pressure 

Handwand in 

Indoor 

Environments

0.0078 lb ai per 

gallon 10 gallons 0.078 1.1 0.0011 54

1 Based on the label directions (2.6 solid ounces of product added to 10 gallons of water) and 50% a.i. in the product.

2 Based on the label directions.

3 Amount ai handled = Application Rate (lb ai/gallon) *Gallons Applied 

4 Unit Exposure Value for Mix Load Apply Wettable Powder Using a Low Pressure Handwand (2012 Residential SOPs).

5 Daily Dose = [Amount ai Handled (lb) * Unit Exposure (mg/lb ai)] ÷ Body Weight (80 kg).

6 Inhalation MOE = HED (0.059 mg/kg/day for 8 hour exposures) ÷ Daily Dose (mg/kg/day).
Page 22 of 64

Exposure Duration: Residential exposure is expected to be short-term in duration. Intermediateterm exposures are not likely because of the intermittent nature of applications by homeowners. 

Granule ingestion following treatment of turf is considered episodic in duration. Because the 

soil half-life is relatively short, intermediate-term exposures are not expected. 

Residential Post-application Non-Cancer Exposure and Risk Equations

The algorithms used to estimate residential post-application exposure and dose can be found in 

Appendix A and the 2012 Residential SOPs7.

Combining Exposure and Risk Estimates

The incidental oral scenarios (i.e., hand-to-mouth and object-to-mouth) should be considered 

inter-related and it is likely that they occur interspersed amongst each other across time. 

Combining these scenarios would be overly-conservative because of the conservative nature of 

each individual assessment. This assessment should be considered a protective estimate of 

potential post-application exposure for children 1 to < 2 years old. 

Characterization Granule Ingestion

Ingestion of granules is considered an episodic event and not a routine behavior. Because HED 

does not believe that this would occur on a regular basis, our concern for human health is related 

to acute poisoning rather than short-term residue exposure. Therefore, an acute dietary dose is 

used to estimate exposure and risk resulting from episodic ingestion of granules. 

Summary of Residential Post-application Non-Cancer Exposure and Risk Estimates

The registered residential uses of azoxystrobin do not result in any risks of concern for postapplication incidental oral exposures. 

Table 5.2.1. Residential Post-application Non-cancer Exposure and Risk Estimates for the Conventional Uses of 

Azoxystrobin.

Lifestage

Post-application Exposure Scenario Application Rate1 Dose (mg/kg/day)2 MOEs3

Use Site Route of Exposure

Children 1 to 

< 2 years old

Turf (Liquid/Sprays)

Hand-to-Mouth

0.99 lb ai/A

0.0151 2,300

Object-to-Mouth 0.0046 76,000

Soil Ingestion 0.000034 1,00,000

Turf (Granules)

Hand-to-Mouth

0.95 lb ai/A

0.0014 24,000

Object-to-Mouth 0.000088 400,000

Soil Ingestion 0.000032 1,100,000

Granule Ingestion 0.31% ai 0.085 2,400

1 Based on registered or proposed labels (Reg. No. 89442-21, and 100-1275).

2 Dose (mg/kg/day) algorithms provided in 2012 Residential SOPs (http://www2.epa.gov/pesticide-science-and-assessing-pesticiderisks/standard-operating-procedures-residential-pesticide).

3 MOE = POD (mg/kg/day) ÷ Dose (mg/kg/day). Incidental oral POD = 35 mg/kg/day where LOC = 100 ; Incidental episodic oral POD = 200 

mg/kg/day, where LOC = 300

5.2.2 Residential Post-Application Exposure/Risk Estimates – Antimicrobial

Azoxystrobin Uses 

 

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There is the potential for residential post-application incidental oral exposures to vinyl flooring 

made from azoxystrobin treated/impregnated vinyl and plastic toys manufactured from 

azoxystrobin treated plastic. There is the potential for residential post-application incidental oral 

and inhalation exposures from indoor mold spray treatment and indoor carpet and hard surface 

treatment for mold. 

5.2.2.1 Incidental Oral Exposure from Treated/Impregnated Vinyl Flooring

Vinyl tiles used for flooring can be treated with azoxystrobin during the manufacturing process. 

Therefore, post-application incidental oral exposures to treated/impregnated vinyl flooring may 

occur. Children (1 to < 2 years old) are the index lifestage for this scenario. Because the 

Residential SOPs deal primarily with conventional pesticides that are applied to surfaces, rather 

than antimicrobials that are incorporated into materials, modifications were made to the surface 

residue equations to include an availability factor (AF) of 0.5 percent8to account for the fact that 

only a small portion of the antimicrobial ingredient incorporated into plastic is at the surface and 

available for exposure. See Appendix A for the equations and assumptions to estimate the 

incidental oral exposures from treated vinyl flooring. 

Treated Vinyl Risk Summary

The MOE for incidental oral hand to mouth exposure to azoxystrobin treated vinyl flooring is 

summarized in Table 5.2.2.1. The MOE is 610 and the risk is not of concern. 

Table 5.2.2.1. Incidental Oral Hand to Mouth MOE for Azoxystrobin Treated Vinyl Flooring.

Application Rate

(percent by 

weight)

Surface 

Residue1

(mg/cm2)

Transfer 

Factor

Hand 

Residue2

(mg/cm2)

Exposure3

(mg/day)

Dose4

(mg/kg/day)

Incidental 

Oral MOE

(LOC = 100)5

0.225 0.0044 1.0 0.0044 0.65 0.057 610

1. Surface Residue (SR) = Density (1300 mg/cm3) * Vinyl Thickness (0.3 cm) * Weight Fraction (AR/100) * Availability Factor (0.5/100)

2. Hand Residue (HR) = SR (mg/cm2) * Transfer Factor (1.0)

3. Exposure = HR (mg/cm2) * FM (0.13) * Surface Area Hand (SAH)(150 cm2) * Exposure Time (ET) (2 hrs) * NR (4/hr) * [1 – (1-SE (0.48)FHtM 

(20/hr)/NR(4)]}

4. Dose = Exposure (mg/day) / BW (11 kg)

5. MOE = NOAEL / Dose where the NOAEL is 35 mg/kg/day and the target MOE is 100.

5.2.2.2 Post-Application Exposure from Indoor Spray Antimicrobial Applications 

There is potential for incidental oral exposures for children’s hand-to-mouth contact with carpet 

and hard surfaces treated with azoxystrobin mold spray, as well as, post-application inhalation 

exposure from indoor applications of surface sprays for adults and children. 

Residential Post-application Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the residential 

post-application risk assessment. Each assumption and factor is detailed in the 2012 Residential 

SOPs6.

Application Rate: The registered application rates of azoxystrobin are listed in Table 4.1. The 

 

8 The availability factor is based on migration calculations using Fick’s 1st and 2nd laws of diffusion as programmed in the Arthur D. Little 

Polymer Migration Estimation Model (AMEM) model. 
Page 24 of 64

treatment solution ai density is 0.0078 lb ai per gallon based on the label. The spray volume is 

0.004 gallons per square foot based on the label coverage recommendation of 250 square feet per

gallon

Exposure Duration: Residential exposure is expected to be short-term in duration. Intermediateterm exposures are not likely because of the intermittent nature of applications by homeowners. 

Residential Post-application Non-Cancer Exposure and Risk Equations

The algorithms used to estimate residential post-application exposure and dose can be found in 

Appendix A and the 2012 Residential SOPs9.

Indoor Antimicrobial Spray Uses of Azoxystrobin Risk Summary

The MOEs for post-application exposure to the indoor uses of azoxystrobin are summarized in 

Table 5.2.2. Incidental oral exposures were not combined from both treated hard surfaces and 

carpets because of the already conservative assumptions inherent in the assessment. When 

assessing individual short-term residential post-application exposure scenarios, EPA assumes 

exposure occurs to zero-day residues (i.e., day of application residues) day after day, for the 

same amount of time every day (i.e., no day to day variation). These exposure estimates are then 

compared to points of departure that are typically based on weeks of dosing in test animals. For 

azoxystrobin, the short-term risk assessment has the additional conservatism of basing the level 

of concern for short-term exposure (30-days) on a toxicity study involving continuous exposure 

over 10 weeks for parental animals; and at least 21 days for pups while also being exposed in 

utero.

 

Table 5.2.2.2. Residential Post-application Non-cancer Exposure and Risk Estimates for the Indoor 

Antimicrobial Uses of Azoxystrobin.

Lifestage

Post-application Exposure Scenario Application Rate1 Dose (mg/kg/day)2 MOEs

(LOC = 100)3 Use Site Route of Exposure

Adult Indoor Mold Surface Directed 

Sprays Inhalation 0.0078 lb ai/gal 0.0000000023 8,800,000

Children 1 to 

< 2 years old

Indoor Mold Surface Directed 

Sprays Inhalation

0.0078 lb ai/gal or 

0.000031 lb ai/ft2

0.0000000084 2,400,000

Indoor Surface Directed Sprays –

Carpets Hand-to-Mouth 0.0902 390

Indoor Surface Directed Sprays –

Hard Surfaces Hand-to-Mouth 0.0301 1,100

Indoor Surface Directed Sprays –

Carpets Object-to-Mouth 0.013 2,700

Indoor Surface Directed Sprays –

Hard Surfaces Object-to-Mouth 0.0087 4,000

1 Based on registered or proposed labels (Reg. No. 89442-21, 100-1275, and 100-1093).

2 Dose (mg/kg/day) algorithms provided in 2012 Residential SOPs (http://www2.epa.gov/pesticide-science-and-assessing-pesticiderisks/standard-operating-procedures-residential-pesticide).

3 MOE = POD (mg/kg/day) ÷ Dose (mg/kg/day). Incidental oral POD = 35 mg/kg/day, inhalation HED (0.02 mg/kg/day). 

5.2.2.3 Incidental Oral Exposure from Plastic Toys 

Plastics and polymers can be treated with an azoxystrobin during production and these plastics 

 

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and polymers can be subsequently used to manufacture toys. Therefore, unless the label 

specifically prohibits use in plastics and polymers used to manufacture toys, it is assumed 

children’s post-application incidental oral exposures to treated toys may occur. It is assumed 

that not all plastic toys are treated with azoxystrobin and the toys that are treated will not be used 

every day, therefore, exposure would occur intermittently. Thus, only short-term exposures 

durations were assessed. Children (1 to < 2 years old) are the index lifestage for this scenario.

See Appendix A for the assumptions and equations for calculating incidental exposure from 

plastic toys. 

Treated Toys Risk Summary

The MOE for incidental oral hand to mouth exposure to azoxystrobin treated toys is summarized 

in Table 5.2.3. The MOE is 2,500 and the risk is not of concern. 

Table 5.2.2.3. Incidental Oral Object to Mouth MOE for Azoxystrobin Treated Toys.

Weight Fraction Surface 

Residue1

(mg/cm2)

Object Residue2

(mg/cm2)

Exposure3

(mg/day)

Dose4

(mg/kg/day)

Incidental Oral 

MOE

(LOC = 100)5

0.00225 0.0011 0.0011 0.16 0.014 2,500

1 Surface Residue (SR) = WF (0.00225) * Toy Weight (50 grams) * 1000 mg/gm * Availability Factor (0.5/100)

 Toy Surface Area (500 cm2)

2 Object Residue (OR) = SR (mg/cm2) * Transfer Factor (1.0)

3 Exposure = OR (mg/cm2) * Surface Area Mouthed (SAM)(10 cm2) * Exposure Time (ET) (4 hr) * NR (4/hr) * [1 – (1-SE (0.48)FHtM (14/hr)/NR(4)]}

4 Dose = Exposure (mg/day) / BW (11 kg)

5 MOE = NOAEL / Dose where the NOAEL is 35 mg/kg/day and the target MOE is 100.

5.3 Residential Risk Estimates for Use in Aggregate Assessment

Table 5.3 reflects the residential risk estimates that are recommended for use in the aggregate 

assessment for azoxystrobin. An adult aggregate assessment including residential handler 

inhalation exposures will not be conducted because effects seen in the route-specific inhalation 

toxicity study differ from those seen via the oral route; therefore residential exposures will not be 

aggregated with dietary exposures for adults. The recommended residential exposure for use 

in the children 1 to <2 years old aggregate assessment reflects hand-to-mouth incidental 

oral exposures from treated carpets. 

Ingestion of granules is considered an episodic event and not a routine behavior. Because HED 

does not believe that this would occur on a regular basis, our concern for human health is related 

to acute poisoning rather than short-term residue exposure. Therefore, an acute dietary dose is 

used to estimate exposure and risk resulting from episodic ingestion of granules. For these same 

reasons, the episodic ingestion scenario is not recommended for inclusion in the aggregate 

assessment. 
Page 26 of 64

Table 5.3. Recommended Scenarios for the Residential Exposures for the Azoxystrobin 

Aggregate Assessment.1

Lifestage

Post-application Exposure (mg/kg/day) Residential Postapplication Total 

Exposure 

(mg/kg/day)2

Residential 

Postapplication 

MOE3

Inhalation Oral

Short-Term

Child 1 to 

<2 years old N/A 

0.0902

(Hand-to-Mouth exposure from treated 

carpets)

0.0902 390

1 N/A = not applicable. Children handler exposures are not expected. For children 1 to < 2 years old, total residential exposure 

represents high-end post-application incidental oral exposure (Tables 5.2.2.2). 

2 Post-application exposure represents high-end or incidental oral exposure for the relevant exposure duration.

3 Total MOE = NOAEL (35 mg/kg/day) ÷ (Incidental Oral Exposure). 

Since the estimated residential turf post-application exposure for residential turf using default 

TTR values for azoxystrobin is minimal in comparison to the level of concern (i.e., the calculated 

MOE is greater than 10 times higher than the level of concern, MOE = 2,300 compared to the 

LOC of 100); EPA is recommending that 40CFR TTR data are not needed. In this instance, it is

unlikely that chemical-specific TTR data would be needed to further refine exposure assessments 

or would add appreciably to our general understanding of the availability of turf transferable 

pesticide residues.

Because no dermal hazard was identified for azoxystrobin, a residential post-application 

assessment on ornamentals was not conducted; therefore a DFR study is not needed for

azoxystrobin at this time. 

6.0 Non-Occupational Spray Drift Exposure and Risk Estimates

Off-target movement of pesticides can occur via many types of pathways and it is governed by a 

variety of factors. Sprays that are released and do not deposit in the application area end up offtarget and can lead to exposures to those it may directly contact. They can also deposit on 

surfaces where contact with residues can eventually lead to indirect exposures (e.g., children 

playing on lawns where residues have deposited next to treated fields). The potential risk 

estimates from these residues can be calculated using drift modeling coupled with methods 

employed for residential risk assessments for turf products.

The approach to be used for quantitatively incorporating spray drift into risk assessment is based 

on a premise of compliant applications which, by definition, should not result in direct exposures 

to individuals because of existing label language and other regulatory requirements intended to 

prevent them.10 Direct exposures would include inhalation of the spray plume or being sprayed 

directly. Rather, the exposures addressed here are thought to occur indirectly through contact 

with impacted areas, such as residential lawns, when compliant applications are conducted. 

Given this premise, exposures for children (1 to 2 years old) and adults who have contact with 

turf where residues are assumed to have deposited via spray drift thus resulting in an indirect 

exposure are the focus of this analysis analogous to how exposures to turf products are 

considered in risk assessment. 

 

10 This approach is consistent with the requirements of the EPA’s Worker Protection Standard which, when included on all 

labels, precludes direct exposure pathways.
Page 27 of 64

Several azoxystrobin products have existing labels for use on turf, thus it was considered 

whether the risk assessment for that use may be considered protective of any type of exposure 

that would be associated with spray drift. It should be noted that the registered residential uses 

on turf result in exposure greater than potential exposure from spray drift; therefore, no new 

residential assessment needs to be completed. If the maximum application rate on crops adjusted 

by the amount of drift expected is less than or equal to existing turf application rates, the existing 

turf assessment is considered protective of spray drift exposure. The currently registered

maximum single application rate of azoxystrobin is 0.33 lb ai/A. The highest degree of spray 

drift noted for any application method immediately adjacent to a treated field (Tier 1 output from 

the aerial application using fine to medium spray quality) results in a deposition fraction of 0.26 

of the application rate. A quantitative spray drift assessment for azoxystrobin is not required 

because the maximum application rate to a crop/target site multiplied by the adjustment factor 

for drift of 0.26 is less than the maximum direct spray residential turf application rate of 0.99 lb 

ai/A11 for any azoxystrobin products. The turf post-application MOEs have been previously 

assessed and are based on the revised SOPs for Residential Exposure Assessment (i.e., see above 

in Section 5.2). 

7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates

Volatilization of pesticides may be a source of post-application inhalation exposure to 

individuals nearby 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, and received the SAP’s final report on 

March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The 

agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a 

subsequent Volatilization Screening Analysis 

(http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219). 

During Registration Review, the agency will utilize this analysis to determine if data (i.e., flux 

studies, additional route-specific inhalation toxicological studies) or further analysis is needed

for azoxystrobin.

Per the Residential SOPs, a quantitative residential post-application inhalation exposure 

assessment was performed in the residential post-application section of the ORE chapter. There 

were no risks of concern identified for residential post-application inhalation exposures using 

conservative inputs and assumptions. There are no post-application inhalation residential risk 

estimates of concern at this time. 

8.0 Occupational Exposure and Risk Estimates

8.1 Occupational Handler Exposure/Risk Estimates – Conventional Azoxystrobin Uses 

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 

 

11 0.33 lb ai/A x 0.26 ≤ 0.99 lb ai/A
Page 28 of 64

applications and exposures can vary depending on the specifics of each task. Job requirements 

(amount of chemical used in each 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 application event. 

Based on the anticipated use patterns and current labeling, types of equipment and techniques 

that can potentially be used, occupational handler exposure is expected from the proposed uses. 

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

scenarios listed in Tables 8.1.1 – 8.1.6.

Occupational Handler Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the occupational 

handler risk assessments. Each assumption and factor is detailed below on an individual basis.

Application Rate: The registered application rates for azoxystrobin are listed in Table 4.1. 

Unit Exposures: It is the policy of HED to use the best available data to assess handler exposure. 

Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, 

include PHED 1.1, the Policy 14 for Seed Treatment, AHETF database, the ORETF database, 

the Post-Harvest SOP, or other registrant-submitted occupational exposure studies. Some of 

these data are proprietary (e.g., AHETF data), and subject to the data protection provisions of 

FIFRA. The standard values recommended for use in predicting handler exposure that are used 

in this assessment, known as “unit exposures”, are outlined in the “Occupational Pesticide 

Handler Unit Exposure Surrogate Reference Table12”, which, along with additional information 

on HED policy on use of surrogate data, including descriptions of the various sources, can be 

found at the Agency website13.

Area Treated or Amount Handled: The area treated/amount handled are based on ExpoSAC 

Policy 9.1, the Post-Harvest SOP, and the SOPs for Seed Treatment. Inputs may be found in 

Appendix C. 

Exposure Duration: HED classifies exposures from 1 to 30 days as short-term and exposures 30 

days to six months as intermediate-term. Exposure duration is determined by many things, 

including the exposed population, the use site, the pest pressure triggering the use of the 

pesticide, and the cultural practices surrounding that use site. For most agricultural uses, it is 

reasonable to believe that occupational handlers will not apply the same chemical every day for 

more than a one-month time frame; however, there may be a large agribusiness and/or 

commercial applicators who may apply a product over a period of weeks (e.g., completing 

multiple applications for multiple clients within a region). 

For azoxystrobin, based on the existing uses, both short- and intermediate-term exposures are 

expected for occupational handlers because it could be applied multiple times per season to many 

 

12 Available: http://www.epa.gov/opp00001/science/handler-exposure-table.pdf

13 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Page 29 of 64

registered crops. However, the occupational inhalation POD is applicable to both durations; 

therefore the assessment is protective of both short- and intermediate-term exposures. 

Mitigation/Personal Protective Equipment: Estimates of dermal and inhalation exposure were 

calculated for various levels of PPE. Results are presented for “baseline,” defined as a single 

layer of clothing consisting of a long sleeved shirt, long pants, shoes plus socks, no protective 

gloves, and no respirator, as well as baseline with various levels of PPE as necessary (e.g., 

gloves, respirator, etc). The registered azoxystrobin labels require baseline attire (long sleeved 

shirts, long pants, shoes, and socks) and in addition to PPE including chemical resistant gloves; 

and in some cases, protective eyewear, a respirator, or double layer clothing. Only liquid 

formulation labels that are co-formulated with other active ingredients require respirators, and no 

dry flowable products require the use of respirators when handling azoxystrobin. 

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations

The algorithms used to estimate non-cancer exposure and dose for occupational handlers can be 

found in Appendix A.

Combining Exposures/Risk Estimates

There was no dermal hazard identified for azoxystrobin; therefore a dermal exposure assessment 

was not conducted and dermal exposures were not combined with inhalation exposures. 

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates

There are some occupational handler risk estimates of concern for the registered uses of 

azoxystrobin at baseline, PPE, and engineering control mitigation. The LOC for occupational 

inhalation risk estimates is an MOE of 300. At baseline, occupational handler inhalation MOEs 

ranged from 1.1 to 50,000. 

The following scenarios are of concern with baseline PPE (no respirator): 

 Mixing/loading dry flowables for aerial, airblast, groundboom, and chemigation 

application to all registered crops at maximum registered application rates; 

 Mixing/loading granules for aerial application to sod; 

 Mixing/loading granules for tractor-drawn spreader applications to sod and golf course 

fairways, greens, and tees. 

 Mixing/loading liquids for aerial application to orchards/vineyards, sod, typical field 

crops, and high acreage field crops at maximum registered application rates; 

 Mixing/loading liquids for chemigation application to orchards/vineyards, sod, typical 

field crops, high acreage field crops; 

 Mixing/loading liquids for groundboom application to sod and high acreage field crops; 

 Applying sprays with airblast application equipment to nursery ornamentals and 

orchards/vineyards; 

 Applying sprays with groundboom application equipment to sod; golf course fairways, 

tees, and greens; typical field crops; and high acreage field crops; 

 Applying granules with aerial application equipment to sod; 

 Applying granules with a tractor-drawn spreader to sod, and golf course fairways, greens, 

and tees; 
Page 30 of 64

 Flagging for aerial application to sod during liquid and granular applications; 

 Mixing/loading/applying dry flowable or liquid formulations with a backpack sprayer to 

orchard/vineyards, Christmas tree farms, and nursery ornamentals; 

 Mixing/loading/applying dry flowable or liquid formulations using a manually 

pressurized handwand to Christmas tree farms, nursery ornamentals, and landscaping; 

 Mixing/loading/applying dry flowable or liquid formulations using a mechanically 

pressurized handwand to orchard/vineyards, Christmas tree farms, nursery ornamentals, 

golf courses, landscaping, and typical field crops; 

 Mixing/loading/applying liquids with a manually pressurized handwand to greenhouse 

ornamentals; 

 Mixing/loading/applying liquids with a mechanically pressurized handwand to 

orchards/vineyards, Christmas tree farms, nursery ornamentals, greenhouse ornamentals, 

landscaping, and typical field crops; 

 Loading/applying granule formulations with a rotary spreader to golf courses; 

 Mixing/loading for post-harvest treatments in a closed system to citrus; 

 Mixing/loading dry flowable formulations in an automated system for post-harvest 

treatment of bananas, 

 Mixing/loading liquids in an automated system for post-harvest treatment for citrus; 

 Applying direct post-harvest sprays using a mechanically pressurized handgun to citrus 

and bananas; 

 Loading/applying, sewing, bagging, and multiple activities for numerous liquid seed 

treatment uses of azoxystrobin; 

 Planting treated barley, legume vegetable, peanut, potato, triticale, tuberous and corm 

vegetable, turf, and wheat seeds with liquid formulations of azoxystrobin; 

 Loading/applying, sewing, bagging, multiple activities for dust seed treatment 

applications to peanuts; 

 Planting peanut seeds treated with dust formulations; 

 Loading/applying, sewing, bagging, and multiple activities for cotton dry flowable seed 

treatment uses of azoxystrobin; and 

 Sorting and packing following post-harvest treatment of citrus and bananas.

The following scenarios are of concern with maximum available personal protective equipment

or engineering controls: 

 Mixing/loading dry flowable formulations for aerial or chemigation application to sod 

and high acreage field crops; 

 Mixing/loading granule formulations for aerial application to sod; 

 Mixing/loading/applying dry flowable formulations for backpack sprayer application to 

landscaping; 

 Mixing/loading/applying dry flowable formulations for mechanically pressurized 

handgun applications to golf courses, landscaping, and typical field crops. 

 Mixing/loading/applying liquids for backpack application to landscaping and turf; 

 Mixing/loading/applying liquids for mechanically pressurized handgun applications to 
Page 31 of 64

typical field crops and greenhouse ornamentals; 

 Mixing/loading liquids for post-harvest treatment of citrus in a closed automated system; 

 Mixing/loading liquids for post-harvest treatment of citrus in an open automated system; 

 Mixing/loading/applying liquids for post-harvest treatment of citrus using a mechanically 

pressurized handgun. 

 Loading/applying liquid formulation to sunflower seeds; 

 Sewing bags of treated sunflower seeds following liquid seed treatment; 

 Multiple activities following/during liquid seed treatment for sunflower seed treatment; 

 Planting potato, tuberous and corm vegetable, and turf seeds following liquid seed 

treatment; 

 Loading/applying, sewing, bagging, and multiple activities following/during dust 

treatment of peanut seeds; 

 Loading/applying, sewing, bagging, and multiple activities following dry flowable 

formulation treatment of cotton seeds. 

The Agency matches quantitative occupational exposure assessment with appropriate 

characterization of exposure potential. While HED presents quantitative risk estimates for human 

flaggers where appropriate, agricultural aviation has changed dramatically over the past two 

decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of 

their membership, the use of GPS for swath guidance in agricultural aviation has grown steadily 

from the mid 1990’s. Over the same time period, the use of human flaggers for aerial pesticide 

applications has decreased steadily from ~15% in the late 1990’s to only 1% in the most recent 

(2012) NAAA survey. The Agency will continue to monitor all available information sources to 

best assess and characterize the exposure potential for human flaggers in agricultural aerial 

applications.

HED has no data to assess exposures to pilots using open cockpits. The only data available is for 

exposure to pilots in enclosed cockpits. Therefore, risks to pilots are assessed using the 

engineering control (enclosed cockpits) and baseline attire (long-sleeve shirt, long pants, shoes, 

and socks); per the Agency’s Worker Protection Standard stipulations for engineering controls, 

pilots are not required to wear protective gloves for the duration of the application. With this 

level of protection, there are currently no risk estimates of concern for applicators, except for 

aerial application of granules to sod.
Page 32 of 64

Table 8.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1 Maximum

Application Rate2

Inhalation MOE

(LOC = 300)

Baseline PF5 Respirator PF10 Respirator Engineering Control

Mixer/Loader

Mixing/Loading Dry Flowables for Aerial 

Application

Nursery Ornamentals 0.25 lb ai/A 35 180 350 2,300

Orchards/Vineyards 0.25 lb ai/A 6.0 30 60 390

Sod 0.95 lb ai/A 1.6 7.9 16 100

Field Crop, Typical 0.33 lb ai/A 4.6 23 46 300

Field Crop, High Acreage 0.4 lb ai/A 1.1 5.5 11 72

Mixing/Loading Dry Flowables for Airblast 

Application

Nursery Ornamentals 0.25 lb ai/A 110 530 1,100 6,900

Orchards/Vineyards 0.25 lb ai/A 53 260 530 3,400

Mixing/Loading Dry Flowables for Chemigation 

Application

Orchards/Vineyards 0.25 lb ai/A 6.0 30 60 390

Sod 0.95 lb ai/A 1.6 7.9 16 100

Field Crop, Typical 0.33 lb ai/A 4.6 23 46 300

Field Crop, High Acreage 0.4 lb ai/A 3.8 19 38 250

Nursery Ornamentals 0.25 lb ai/A 35 180 350 2,300

Mixing/Loading Dry Flowables for Groundboom 

Application

Golf course (tees and greens) 0.95 lb ai/A 110 560 1,100 7,200

Golf course (fairways, tees, and greens) 0.95 lb ai/A 14 69 140 900

Field-Grown Ornamental Crops 0.25 lb ai/A 53 260 530 3,400

Nursery Ornamentals 0.25 lb ai/A 35 180 350 2,300

Sod 0.95 lb ai/A 6.9 35 69 460

Orchards/Vineyards 0.25 lb ai/A 53 260 530 3,400

Field Crop, Typical 0.33 lb ai/A 20 100 200 1,300

Field Crop, High Acreage 0.4 lb ai/A 6.6 33 66 430

Mixing/Loading Granules for Aerial Application Sod 0.95 lb ai/A 15 73 150 300

Mixing/Loading Granules for Tractor-Drawn 

Spreader Applications

Golf Course (Fairways, Tees, Greens) 0.95 lb ai/A 130 640 1,300 2,600

Golf Course (Tees and Greens) 0.95 lb ai/A 1,000 5,100 10,000 21,000

Sod 0.95 lb ai/A 64 230 640 1,300

Mixing/Loading Liquids for Aerial Application

Nursery Ornamentals 0.25 lb ai/A 1,400 7,200 14,000 6,600

Orchards/Vineyards 0.25 lb ai/A 250 1,200 2,500 1,100

Sod 0.99 lb ai/A 62 310 620 290

Field Crop, Typical 0.33 lb ai/A 190 930 1,900 860

Field Crop, High Acreage 0.4 lb ai/A 45 220 450 210
Page 33 of 64

Table 8.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1 Maximum

Application Rate2

Inhalation MOE

(LOC = 300)

Baseline PF5 Respirator PF10 Respirator Engineering Control

Mixing/Loading Liquids for Airblast Application

Nursery Ornamentals 0.25 lb ai/A 4,300 22,000 43,000 20,000

Orchards/Vineyards 0.25 lb ai/A 2,200 11,000 22,000 9,900

Mixing/Loading Liquids for Chemigation 

Application

Orchards/Vineyards 0.25 lb ai/A 250 1,200 2,500 1,100

Sod 0.99 lb ai/A 62 310 620 290

Field Crop, Typical 0.33 lb ai/A 190 930 1,900 860

Field Crop, High Acreage 0.4 lb ai/A 150 770 1,500 710

Greenhouse Ornamentals 0.26 lb ai/A 1,400 6,900 14,000 6,400

Nursery Ornamentals 0.25 lb ai/A 1,400 7,200 14,000 6,600

Mixing/Loading Liquids for Groundboom 

Application

Golf Course (Tees and Greens) 0.99 lb ai/A 4,400 22,000 44,000 20,000

Golf Course (Fairways, Tees, Greens) 0.99 lb ai/A 550 2,700 5,500 2,500

Field-Grown Ornamentals 0.25 lb ai/A 2,200 11,000 22,000 9,900

Nursery Ornamentals 0.25 lb ai/A 1,400 7,200 14,000 6,600

Greenhouse Ornamentals 0.26 lb ai/A 1,400 6,900 14,000 6,400

Sod 0.99 lb ai/A 270 1,400 2,700 1,300

Orchards/Vineyards 0.25 lb ai/A 2,200 11,000 22,000 9,900

Field Crop, Typical 0.33 lb ai/A 820 4,100 8,200 3,800

Field Crop, High Acreage 0.4 lb ai/A 270 1,300 2,700 1,200

Applicator

Applying Sprays with Aerial Application Equipment

Nursery Ornamentals 0.25 lb ai/A

N/A

32,000

Orchards/Vineyards 0.25 lb ai/A 5,400

Sod 0.99 lb ai/A 1,400

Field Crop, Typical 0.33 lb ai/A 4,100

Field Crop, High Acreage 0.4 lb ai/A 990

Applying Sprays with Airblast Application 

Equipment

Nursery Ornamentals 0.25 lb ai/A 98 490 980 6,800

Orchards/Vineyards 0.25 lb ai/A 49 250 490 3,400

Applying Sprays with Groundboom Application 

Equipment

Golf Course (Tees and Greens) 0.99 lb ai/A 1,400 6,900 14,000 39,000

Golf Course (Fairways, Tees, Greens) 0.99 lb ai/A 170 860 1,700 4,800

Field-Grown Ornamentals 0.25 lb ai/A 680 3,400 6,800 19,000

Nursery Ornamentals 0.25 lb ai/A 450 2,300 4,500 13,000

Greenhouse Ornamentals 0.26 lb ai/A 440 2,200 4,400 12,000

Sod 0.99 lb ai/A 86 430 860 2,400
Page 34 of 64

Table 8.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1 Maximum

Application Rate2

Inhalation MOE

(LOC = 300)

Baseline PF5 Respirator PF10 Respirator Engineering Control

Orchards/Vineyards 0.25 lb ai/A 680 3,400 6,800 19,000

Field Crop, Typical 0.33 lb ai/A 260 1,300 2,600 7,200

Field Crop, High Acreage 0.4 lb ai/A 85 430 850 2,400

Applying Granules with Aerial Application 

Equipment

Sod 0.95 lb ai/A N/A 19

Applying Granules with a Tractor-Drawn Spreader

Golf Course (Fairways, Tees, Greens) 0.95 lb ai/A 180 900 1,800 980

Golf Course (Tees and Greens) 0.95 lb ai/A 1,400 7,200 14,000 7,900

Sod 0.95 lb ai/A 90 450 900 490

Flagger

Flagging for Aerial Applications (Sprays) Sod 0.95 lb ai/A 71 350 710

N/A

Flagging for Aerial Applications (Granules) Sod 0.95 lb ai/A 170 820 1,700

Mixer/Loader/Applicator

Mixing/Loading/Applying Dry Flowable or Liquid 

Formulations with Backpack Sprayer

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals (Ground 

Directed)

0.025 lb ai/gal

1,800 9,100 18,000 N/A

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals (Broadcast)

0.025 lb ai/gal 120 600 1,200

Landscaping (Plants, Flowers, Trees, N/A

Turf) (Broadcast Treatment)

0.119 lb ai/gal 25 130 250

Landscaping Turf (Spot Treatment) 0.119 lb ai/gal 380 1,900 3,800

Mixing/Loading/Applying Dry Flowable or Liquid 

Formulations with a Manually Pressurized 

Handwand

Christmas Tree Farm, Nursery 

Ornamentals (Broadcast) 0.025 lb ai/gal 270 1,400 2,700

N/A

Landscaping (Plants, Flowers, Trees, 

Turf)

0.119 lb ai/gal 58 290 580

Mixing/Loading/Applying Dry Flowable 

Formulations with a Mechanically Pressurized 

Handwand

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals 0.025 lb ai/gal 38 190 380

Golf Course (Tees, Greens, Fairways) 0.95 lb ai/A 24 120 240 N/A

Landscaping (Trees, Shrubs, Bushes) 0.119 lb ai/gal 8 40 79

Field Crop, Typical 0.033 lb ai/gal 29 140 290

Mixing/Loading/Applying Liquids with a Manually 

Pressurized Handwand Greenhouse Ornamentals 0.026 lb ai/gal 260 1,300 2,600 N/A

Mixing/Loading/Applying Liquids with a 

Mechanically Pressurized Handwand

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals 0.025 lb ai/gal 38 190 380

N/A

Greenhouse Ornamentals 0.017 lb ai/gal 4 20 40
Page 35 of 64

Table 8.1.1. Occupational Handler Non-Cancer Exposure and Risk Estimates for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1 Maximum

Application Rate2

Inhalation MOE

(LOC = 300)

Baseline PF5 Respirator PF10 Respirator Engineering Control

Golf Course (Tees, Greens, Fairways), 

Landscaping Turf, 0.01 lb ai/A 50,000 250,000 500,000

Landscaping (Trees, Shrubs Bushes) 0.01 lb ai/gal 8 40 79

Field Crop, Typical 0.033 lb ai/gal 29 140 290

Loading/Applying Granule Formulations with a 

Rotary Spreader Golf Course (Fairways, Tees, Greens) 0.95 lb ai/A 99 500 990 N/A

1 Assessment is based on maximum registered azoxystrobin application rate for each scenario. Crops were grouped according to registered application rates and applicable exposure scenarios 

to cover all registered use sites. Shaded MOEs represent risk estimates of concern (LOC = 300). 

2 Inhalation MOE = Inhalation HED (mg/kg/day) ÷ Inhalation Dose. Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre 

or gal) × Area Treated or Amount Handled Daily (A or gal/day) ÷ BW (kg). Unit Exposures are outlined in the “Occupational Pesticide Handler Unit Exposure Surrogate Reference 

Table14”, which, along with additional information on HED policy on use of surrogate data, including descriptions of the various sources, can be found at the Agency website15. Area or 

Amount Treated Information is available in ExpoSAC Policy 9.1. Inputs for MOE calculations may be found in Appendix C. 

Table 8.1.2. Occupational Handler Non-Cancer Exposure and Risk Estimates for the Registered Post-Harvest Uses of Azoxystrobin.

Exposure Scenario Crop or Target

Maximum

Application Rate1

Inhalation MOE (LOC = 300)

lb ai/gal solution Baseline5 PF5 PF10

Mixing/Loading For Post-Harvest Treatment 

in a Closed Automated System

Citrus 0.15 15 N/A N/A

Potatoes 0.0000049 460,000 N/A N/A

Bananas 0.00034 6,600 N/A N/A

Mixing/Loading Dry Flowable Formulations 

in an Automated System Bananas 0.00034 62 310 620

Mixing/Loading Liquids in an Automated 

System

Citrus 0.15 5.7 29 57

Bananas2 0.00034 2500 13,000 25,000

Applying Direct Post-Harvest Sprays with a 

Mechanically Pressurized Handgun

Citrus 0.15 0.32 1.6 3.2

Bananas2 0.00034 140 700 1,400

1 Based on registered labels (Reg. No. 89442-21, 100-1098, 100-1093).

2 Based on ExpoSAC Post-Harvest Policy. 

3 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/ gal) × Area Treated or Amount Handled Daily (gal/day) ÷ BW (80 kg).

4 Inhalation MOE = Inhalation NOAEL (mg/kg/day) ÷ Inhalation Dose (mg/kg/day). Shaded MOEs indicated MOEs of concern (LOC = 300).

5 For closed automated system, baseline exposures represent engineering control protection. “Baseline” for all other scenarios represents no respirator. Inputs for MOE calculations may be found in 

Appendix C. 

 

14 Available: http://www.epa.gov/opp00001/science/handler-exposure-table.pdf

15 Available: http://www.epa.gov/pesticides/science/handler-exposure-data.html
Page 36 of 64

Table 8.1.3. Primary Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin – Liquids.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Amount of 

Seed Treated 

(lb/day)3 SOP 

15.1

Inhalation Dose (mg/kg/day) Inhalation MOE 

LOC = 300)

Baseline PF5 PF10 EC Baseline PF5 PF 10 EC 

Loader/Applicator

Corn (field, pop, sweet), Peanuts, 

Bulb Vegetables, Cotton,

Cucurbits, Okra, Ornamental 

Bulbs

0.000244 339,500 0.000352 0.000070 0.000035 0.000045 170 840 1700 1300

Rice 0.000070 302,500 0.000104 0.000018 0.000009 0.000011 570 3300 6600 5200

Barley, Triticale, Wheat, 

Sorghum, 0.000244 360,000 0.000433 0.000075 0.000037 0.000047 140 790 1600 1200

Brassica, Eggplant, Leafy 

Vegetables, Bell Pepper, Non-Bell 

Pepper, Tomato, Watercress, 

Ornamental Seed, Turf

0.000244 3,000 0.000004 0.000001 0.000000 0.00000039 16,000 95000 190000 150000

Leaves of Root and Tuber 

Vegetables, Root Vegetables, 

Tuberous and Corm Vegetables

0.000244 800,000 0.000962 0.000166 0.000083 0.000105 61 360 710 560

Potato 0.000244 800,000 0.018106 0.003123 0.001562 0.000105 3 19 38 560

Legume Vegetables 0.000244 281,250 0.000338 0.000058 0.000029 0.000037 170 1000 2000 1600

Soybean 0.00003 281,250 0.000042 0.0000072 0.000004 0.000005 1,400 8200 16000 13000

Sunflower 0.00244 339,500 0.004082 0.000704 0.000352 0.000445 14 84 170 130

Cotton 0.00018 339,500 0.000301 0.000052 0.000026 0.000033 200 1100 2300 1800

Sewer

Corn (field, pop, sweet), Peanuts, 

Bulb Vegetables, Cotton, 

Cucurbits, Okra, Ornamental 

Bulbs

0.000244 339,500 0.000276 0.000048 0.000024 N/A 210 1200 2500 N/A

Rice 0.00007 302,500 0.000071 0.000012 0.0000061 N/A 840 4800 9700 N/A

Barley, Triticale, Wheat, 

Sorghum, 0.000244 360,000 0.000293 0.000051 0.000025 N/A 200 1200 2300 N/A

Brassica, Eggplant, Leafy 

Vegetables, Bell Pepper, Non-Bell 0.000244 3,000 0.0000024 0.00000042 0.00000021 N/A 24,000 140000 280000 N/A
Page 37 of 64

Table 8.1.3. Primary Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin – Liquids.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Amount of 

Seed Treated 

(lb/day)3 SOP 

15.1

Inhalation Dose (mg/kg/day) Inhalation MOE 

LOC = 300)

Baseline PF5 PF10 EC Baseline PF5 PF 10 EC 

Pepper, Tomato, Watercress, 

Ornamental Seed, Turf,

Leaves of Root and Tuber 

Vegetables, Potato, Root 

Vegetables, Tuberous and Corm 

Vegetables

0.000244 800,000 0.000651 0.000112 0.000056 N/A 91 530 1100 N/A

Legume Vegetables 0.000244 281,250 0.000229 0.000039 0.000020 N/A 260 1500 3000 N/A

Soybean 0.00003 281,250 0.000028 0.0000049 0.000002 N/A 2,100 12000 24000 N/A

Sunflower 0.00244 339,500 0.002761 0.00048 0.000238 N/A 21 120 250 N/A

Cotton 0.00018 339,500 0.000204 0.000035 0.000018 N/A 290 1700 3400 N/A

Bagger

Corn (field, pop, sweet), Peanuts, 

Bulb Vegetables, Cotton, 

Cucurbits, Okra, Ornamental 

Bulbs

0.000244 339,500 0.00019 0.000033 0.000017 N/A 310 1800 3600 N/A

Rice 0.00007 302,500 0.000049 0.0000085 0.0000042 N/A 1,200 7000 14000 N/A

Barley, Triticale, Wheat, 

Sorghum, 0.000244 360,000 0.000204 0.000035 0.000018 N/A 290 1700 3400 N/A

Brassica, Eggplant, Leafy 

Vegetables, Bell Pepper, Non-Bell 

Pepper, Tomato, Watercress, 

Ornamental Seed, Turf,

0.000244 3,000 0.0000017 0.00000029 0.00000015 N/A 35,000 200000 400000 N/A

Leaves of Root and Tuber 

Vegetables, Potato, Root 

Vegetables, Tuberous and Corm 

Vegetables

0.000244 800,000 0.00045 0.000078 0.000039 N/A 130 760 1500 N/A

Legume Vegetables 0.000244 281,250 0.00016 0.000027 0.000014 N/A 370 2100 4300 N/A

Soybean 0.00003 281,250 0.000020 0.0000034 0.0000017 N/A 3,000 17000 35000 N/A

Sunflower 0.00244 339,500 0.0019 0.000331 0.000166 N/A 31 180 360 N/A

Cotton 0.00018 339,500 0.000142 0.000024 0.000012 N/A 420 2400 4800 N/A

Multiple Activities

Corn (field, pop, sweet), Peanuts, 

Bulb Vegetables, Cotton, 

Cucurbits, Okra, Ornamental 

Bulbs

0.000244 339,500 0.00192 0.000331 0.00017 0.000045 31 180 360 1300
Page 38 of 64

Table 8.1.3. Primary Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin – Liquids.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Amount of 

Seed Treated 

(lb/day)3 SOP 

15.1

Inhalation Dose (mg/kg/day) Inhalation MOE 

LOC = 300)

Baseline PF5 PF10 EC Baseline PF5 PF 10 EC 

Rice 0.00007 302,500 0.00049 0.000085 0.000042 0.000011 120 700 1400 5200

Barley, Triticale, Wheat, 

Sorghum, 0.000244 360,000 0.00204 0.000351 0.00018 0.000047 29 170 340 1200

Brassica, Eggplant, Leafy 

Vegetables, Bell Pepper, Non-Bell 

Pepper, Tomato, Watercress, 

Ornamental Seed, Turf,

0.000244 3,000 0.000017 0.0000029 0.0000015 0.00000039 3,500 20000 40000 150000

Leaves of Root and Tuber 

Vegetables, Potato, Root 

Vegetables, Tuberous and Corm 

Vegetables

0.000244 800,000 0.0045 0.00078 0.00039 0.000105 13 76 150 560

Legume Vegetables 0.000244 281,250 0.0016 0.00027 0.00014 0.000037 37 210 430 1600

Soybean 0.00003 281,250 0.00020 0.000034 0.000017 0.0000045 300 1700 3500 13000

Sunflower 0.00244 339,500 0.019 0.0033 0.0017 0.00045 3 18 36 130

Cotton 0.00018 339,500 0.0014 0.00024 0.00012 0.000033 42 240 480 1800

1 Seed Treatment Application rates based on the registered liquid azoxystrobin labels (100-1159, 100-1177, 100-1208, 100-1286, 100-1352, 100-1369, 100-1384, 100-1399, 100-1405, 100-

1449, 100-1450). 

2 Unit Exposures from HED Exposure Science Advisory Council Policy 14: Standard Operating Procedures for Seed Treatment (baseline inhalation = no respirator). Unit Exposures for PF5 

and PF10 respirators were adjusted in the inhalation dose calculation accordingly (baseline inhalation UE ÷ 5 = PF5 UE, etc). 

3 HED default for lb seed treated/planted per day from HED Exposure Science Advisory Council Interim Policy 15.1 and the BEAD memo “Acres Planted Per Day and Seeding Rates of Crops 

Grown in the United States” (J. Becker, March 2011).

4 Daily Inhalation Dose (mg/kg/day) = daily inhalation unit exposure (mg/lb ai) × application rate (lb ai/lb seed) × amount planted (lb seed/day) ÷ body weight (80 kg adult).

5 Inhalation MOE = Inhalation POD (mg/kg/day) ÷ Inhalation Dose (mg/kg/day). Short-term level of concern = 300. Shaded MOEs indicated MOEs of concern (LOC = 300).

Table 8.1.4. Secondary Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin – Liquids.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Inhalation 

UE 

Baseline 

(mg/lb ai)

Amount of 

Seed Planted 

(lb /A)

Acres 

Planted 

(A/day) 

SOP 15

Inhalation Dose (mg/kg/day) Inhalation MOE 

(LOC = 300)

Baseline PF5 PF10 Baseline PF5 PF 10

Planters

Barley 0.000244

0.0034

138 200 0.00033 0.000057 0.000029 180 1,000 2,100

Bell pepper 0.000244 1.39 80 0.0000013 0.00000023 0.00000012 44,000 

260,000 

 

510,000 

Brassica 0.000244 2.64 80 0.0000025 0.00000044 0.00000022 23,000 

130,000 

 

270,000 
Page 39 of 64

Table 8.1.4. Secondary Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin – Liquids.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Inhalation 

UE 

Baseline 

(mg/lb ai)

Amount of 

Seed Planted 

(lb /A)

Acres 

Planted 

(A/day) 

SOP 15

Inhalation Dose (mg/kg/day) Inhalation MOE 

(LOC = 300)

Baseline PF5 PF10 Baseline PF5 PF 10

Bulb 

vegetables 0.000244

0.0034

31 80 0.0000302 0.0000052 0.0000026 2,000 11,000 23,000

Corn 

(field) 0.000244 30 200 0.000071 0.0000123 0.0000061 830 4,800 9,600

Corn (pop) 0.000244 22 200 0.000053 0.0000091 0.0000046 1,100 6,500 13,000

Corn 

(Sweet) 0.000244 33 200 0.000080 0.0000138 0.0000069 740 4,300 8,600

Cotton 0.000244 19 200 0.000045 0.0000078 0.0000039 1,300 7,500 15,000

Cucurbits 0.000244 12 80 0.000011 0.0000019 0.00000096 5,300 31,000 61,000

Eggplant 0.000244 7.56 80 0.0000073 0.0000013 0.0000006 8,100 47,000 94,000

Leafy 

Vegetables 0.000244 0.78 80 0.00000075 0.0000001 0.0000001 78,000 450,000 910,000

Leaves of 

root and 

tuber 

vegetables

0.000244 14 80 0.000013 0.0000023 0.0000012 4,400 26,000 51,000

Legume 

Vegetables 0.000244 327 80 0.00031 0.0000542 0.000027 190 1,100 2,200

Okra 0.000244 23 80 0.000022 0.0000038 0.0000019 2,700 16,000 31,000

Ornamental 

bulbs 0.000244 4.48 80 0.0000043 0.00000074 0.00000037 14,000 79,000 160,000

Ornamental 

seed 0.000244 4.48 80 0.0000043 0.00000074 0.00000037 14,000 79,000 160,000

Peanut 0.000244 228 80 0.00022 0.0000379 0.0000189 270 1,600 3,100

Pepper-non 

bell 0.000244 4.18 80 0.00000402 0.0000007 0.00000035 15,000 85,000 170,000

Potato 0.000244 6,970 300 0.025 0.0043 0.0022 2.3 14 27
Page 40 of 64

Table 8.1.4. Secondary Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin – Liquids.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Inhalation 

UE 

Baseline 

(mg/lb ai)

Amount of 

Seed Planted 

(lb /A)

Acres 

Planted 

(A/day) 

SOP 15

Inhalation Dose (mg/kg/day) Inhalation MOE 

(LOC = 300)

Baseline PF5 PF10 Baseline PF5 PF 10

Rice 0.00007 156 200 0.00011 0.000019 0.0000093 550 3,200 6,300

Root 

Vegetables 0.000244 0.12 80 0.00000011 0.000000020 0.0000000098 520,000 3,000,000 6,000,000

Sorghum 0.0002

0.0034

59 80 0.000046 0.0000080 0.0000040 1,300 7,400 15,000

Soybean 0.00003 167 200 0.000049 0.0000085 0.0000043 1,200 6,900 14,000

Sunflower 0.00244 4.00 80 0.000039 0.0000066 0.0000033 1,500 8,900 18,000

Tomato 0.000244 1.09 80 0.0000011 0.00000018 0.0000000903 56,000 330,000 650,000

Triticale 0.000244 116 200 0.00028 0.0000482 0.0000241 210 1,200 2,400

Tuberous 

and Corm 

Vegetables

0.000244 6,970 300 0.025 0.00434 0.0022 2.3 14 27

Turf 0.000244 5,238 80 0.00504 0.00087 0.00043 12 68 140

Watercress 0.000244 17 80 0.000017 0.0000028 0.0000014 3,600 21,000 42,000

Wheat 0.000244 188 200 0.00045 0.000078 0.000039 130 760 1,500

1 Seed Treatment Application rates based on the registered liquid azoxystrobin labels (100-1159, 100-1177, 100-1208, 100-1286, 100-1352, 100-1369, 100-1384, 100-1399, 100-1405, 100-

1449, 100-1450). 

2 Unit Exposures from HED Exposure Science Advisory Council Policy 14: Standard Operating Procedures for Seed Treatment (baseline inhalation = no respirator). Unit Exposures for PF5 

and PF10 respirators were adjusted in the inhalation dose calculation accordingly (baseline inhalation UE ÷ 5 = PF5 UE, etc). 

3 HED default for lb seed treated/planted per day from HED Exposure Science Advisory Council Interim Policy 15.1 and the BEAD memo “Acres Planted Per Day and Seeding Rates of Crops 

Grown in the United States” (J. Becker, March 2011).

4 Daily Inhalation Dose (mg/kg/day) = daily inhalation unit exposure (mg/lb ai) × application rate (lb ai/lb seed) × amount planted (lb seed/day) ÷ body weight (80 kg adult).

5 Inhalation MOE = Inhalation POD (mg/kg/day) ÷ Inhalation Dose (mg/kg/day). Short-term level of concern = 300. Shaded MOEs indicated MOEs of concern (LOC = 300).
Page 41 of 64

1 Seed Treatment Application rates based on the registered dust azoxystrobin labels (100-1190, 100-1438). 

2 Unit Exposures from HED Exposure Science Advisory Council Policy 14: Standard Operating Procedures for Seed Treatment (baseline inhalation = no respirator). Unit Exposures for PF5 

and PF10 respirators were adjusted in the inhalation dose calculation accordingly (baseline inhalation UE ÷ 5 = PF5 UE, etc). The wettable powder mixing/loading UE (PHED Scenario 

4/PHED Scenario 5) was used a surrogate for loader/applicator, sewer, bagger, and multiple activity scenarios for baseline and engineering control dust exposures. 

3 HED default for lb seed treated/planted per day from HED Exposure Science Advisory Council Interim Policy 15.1 and the BEAD memo “Acres Planted Per Day and Seeding Rates of Crops 

Grown in the United States” (J. Becker, March 2011).

4 Daily Inhalation Dose (mg/kg/day) = daily inhalation unit exposure (mg/lb ai) × application rate (lb ai/lb seed) × amount planted (lb seed/day) ÷ body weight (80 kg adult).

5 Inhalation MOE = Inhalation POD (mg/kg/day) ÷ Inhalation Dose (mg/kg/day). Short-term level of concern = 300. Shaded MOEs indicated MOEs of concern (LOC = 300). 

1 Seed Treatment Application rates based on the registered dust azoxystrobin labels (100-1190, 100-1438). 

2 Unit Exposures from HED Exposure Science Advisory Council Policy 14: Standard Operating Procedures for Seed Treatment (baseline inhalation = no respirator). Unit Exposures for PF5 

and PF10 respirators were adjusted in the inhalation dose calculation accordingly (baseline inhalation UE ÷ 5 = PF5 UE, etc). The wettable powder mixing/loading UE (PHED Scenario 

Table 8.1.5. Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin –Dust Formulations.

Scenario

Application 

Rate (lb 

ai/lb seed)1

Inhalation

UE Baseline

(mg/lb ai)2

Inhalation 

UE 

Engineering 

Control 

(mg/lb ai)2

Amount of 

Seed Treated 

or Planted 

(lb/day)3

Inhalation Dose (mg/kg/day) Inhalation MOE

(LOC = 300)

Baseline4 PF54 PF104 EC4 Baseline5 PF55 PF105 Engineering 

Control5

Loader/Applicator, Sewer, Bagger, Multiple Activities

Peanuts 0.00008 0.043 0.00024 339,500 0.015 0.0029 0.0015 0.0015 4 20 40 40

Planters

Peanuts 0.00008 1.69 N/A 228 0.00062 0.00012 0.000062 N/A 95 480 950 N/A

Table 8.1.6. Seed Treatment Exposure and Risk Estimates for the Registered Uses of Azoxystrobin –Dry Flowable Formulations.

Scenario

Application 

Rate (lb ai/lb 

seed)1

Inhalation UE 

(mg/lb ai)2

Inhalation UE 

Engineering 

Control (mg/lb 

ai)2

Amount of 

Seed Treated 

or Planted 

(lb/day)3

Inhalation Dose (mg/kg/day) Inhalation MOE

(LOC = 300)

Baseline4 PF104 Engineering 

Control4 Baseline5 PF105 Engineering Control5

Loader/Applicator, Sewer, Bagger, Multiple Activities

Cotton 0.0002 0.00896 0.0024 339,500 0.0089 0.00088 0.00024 6.7 67 250

Planters

Cotton 0.0002 0.00896 N/A

19

(lb planted/day)

200 (Acres 

Planted per day 

(SOP 15))

0.000098 N/A N/A 600 N/A N/A
Page 42 of 64

4/PHED Scenario 5) was used a surrogate for loader/applicator, sewer, bagger, and multiple activity scenarios for dust exposures. 

3 HED default for lb seed treated/planted per day from HED Exposure Science Advisory Council Interim Policy 15.1 and the BEAD memo “Acres Planted Per Day and Seeding Rates of Crops 

Grown in the United States” (J. Becker, March 2011).

4 Daily Inhalation Dose (mg/kg/day) = daily inhalation unit exposure (mg/lb ai) × application rate (lb ai/lb seed) × amount planted (lb seed/day) ÷ body weight (80 kg adult).

5 Inhalation MOE = Inhalation POD (mg/kg/day) ÷ Inhalation Dose (mg/kg/day). Short-term level of concern = 300. Shaded MOEs indicated MOEs of concern (LOC = 300).
Page 43 of 64

8.2 Occupational Handler Exposure/Risk Estimates – Antimicrobial Uses 

There is the potential for occupational handler inhalation exposure during the use of 

azoxystrobin as a material preservative in interior and exterior paints, paper, wallboard, ceiling 

tiles, caulks, sealants, adhesives, binders, non-apparel textiles and plastics. The exposure 

duration is assumed to be primarily intermediate to long term because these uses occur in 

manufacturing plants that operate on a year round basis. 

There is also a potential for occupational handler exposure during the application of azoxystrobin 

preserved paints using airless sprayers, brushes and rollers. These exposures are anticipated to 

occur on a short to intermediate term basis because several other preservatives besides 

azoxystrobin are used in paints.

Occupational Handler Exposure Assumptions

The following assumptions were used:

 Paint is a representative material and is protective of the other materials on the label.

 The paint contains 0.31 percent azoxystrobin by weight. 

 One handler treats 2000 gallons of paint per day. This is an AD standard value that is 

based on information provided by the paint industry.

 The paint has a density of 10 lb/gal. 

 One handler applies 5 gallons per day for brush/roller applications and 50 gallons per day

for airless sprayer applications. These are standard AD and HED assumptions.

 The body weight of an adult handler is 80 kg.

Occupational Handler Risk Summary

The occupational handler risk estimate (i.e. MOE) for the material preservation uses of 

azoxystrobin is summarized in Table 8. The MOE is less than the LOC of 300 (i.e. the target 

MOE) for paint manufacturing without respirators which means that the risk is of concern. If a 

PF-10 elastomeric half face respirator is worn, the MOE is increased to 300 and is no longer of 

concern.

The MOEs are also of concern for both airless spray and brush/roller paint application. These 

risks cannot be mitigated with respiratory protection because preserved paints are not EPA 

registered pesticide products and thus do not have labels that could include PPE requirements. 

Table 8.2. Azoxystrobin Occupational Handler Inhalation MOEs for Preserved Paint.

Scenario Application 

Rate1

Amount Paint 

Manufactured or 

Applied (lb/day)2

Amount Ai 

Handled 

(lb/day)

Unit Exposure

(mg/lb ai) 3,4,5

Daily Dose6

(mg/kg/day)

Inhalation 

MOE7

(LOC =300)

Adding Azoxystrobin to Paint During Paint Manufacture

Open pour liquid 

(No Respirator)

0.31% ai by wt 20,000 lb

(2,000 gal x 10 lb/gal)

62

0.0017 0.0013 30

Open pour liquid

(PF10 Respirator) 0.017 0.00013 300
Page 44 of 64

8.3 Occupational Post-application Exposure/Risk Estimates

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical’s degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure.

8.3.1 Occupational Post-application Inhalation Exposure/Risk Estimates

There are multiple potential sources 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 final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The agency has 

evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent 

Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQOPP-2014-0219). During Registration Review, the agency will utilize this analysis to determine 

if data (i.e., flux studies, additional route specific inhalation toxicity studies) or further analysis is 

required for azoxystrobin.

In addition, the Agency is continuing to evaluate the available post-application inhalation 

exposure data generated by the Agricultural Reentry Task Force. Given these two efforts, the 

Agency will continue to identify the need for and, subsequently, the way to incorporate 

occupational post-application inhalation exposure into the agency's risk assessments.

The Worker Protection Standard for Agricultural Pesticides contains requirements for protecting 

workers from inhalation exposures during and after greenhouse applications through the use of 

ventilation requirements.[40 CFR 170.110, (3) (Restrictions associated with pesticide 

applications)] 

Application of Paint Containing Azoxystrobin

Airless sprayer

0.31% ai by wt

500

(50 gal x 10 lb/gal)

1.6 0.560 0.010 6

Brush/Roller 50

(5 gal x 10 lb/gal)

0.16 0.20 0.0004 150

1 Based upon maximum rate listed on label #39967-86.

2 AD Standard Operating Procedures (SOPs) for Occupational Exposure Assessment (March 31, 2011).

3 Unit Exposure value is from AEATF Liquid Pour Study. 

4 Unit Exposure value divided by 10 to account for the use of a PF10 Elastomeric Half Face Respirator.

5 HED Occupational Pesticide Handler Unit Exposure Surrogate Reference Table (March, 2013).

6 Daily Dose = [Amount ai Handled (lb) * Unit Exposure (mg/lb)] ÷ Body Weight (80 kg).

7 MOE = HED (0.059 mg/kg/day for 8 hour 5 day per week exposure at 16.7 liters/minute) ÷ Daily Dose (mg/kg/day).
Page 45 of 64

Occupational Post-Application Inhalation Exposure Data and Assumptions

Although the post-application exposures due to agricultural applications has not been 

quantitatively evaluated, there is the potential for occupational post-application inhalation 

exposures in post-harvest treatment facilities. During automated treatments, dermal and 

inhalation exposure is anticipated for workers performing sorting and packing tasks. Since the 

workers experience exposure following the treatment, this is technically “post-application” 

exposure; however, unlike other post-application activities (e.g., harvesting, scouting, etc.), this 

treatment is not governed by the Worker Protection Standard (WPS) and potential re-entry 

intervals (REIs). Additionally, for workers in the warehouse or packaging facility not directly 

involved in the automated treatment process, there is potential for indirect inhalation exposure. 

Exposures for these various scenarios are assessed using HED ExpoSAC Policy/Guidance

“Assessment of Occupational Exposure for Post-Harvest Commodity Pesticide Treatments” (M. 

Crowley, 23-MAR-2012). A series of assumptions and exposure factors served as the basis for 

completing the occupational post-application risk assessment. Each assumption and factor is 

detailed below on an individual basis. 

Exposure Duration: HED classifies exposures from 1 to 30 days as short-term and exposures 30 

days to six months as intermediate-term. Exposure duration is determined by many things, 

including the exposed population, the use site, the pest pressure triggering the use of the 

pesticide, and the cultural practices surrounding that use site. For most agricultural uses, it is 

reasonable to believe that occupational post-application workers will not apply the same 

chemical every day for more than a one-month time frame; however, there may be a large 

agribusiness and/or commercial applicators who may apply a product over a period of weeks 

(e.g., completing multiple applications for multiple clients within a region). 

For azoxystrobin, based on the existing uses, both short- and intermediate-term exposures are 

expected for occupational handlers in post-harvest facilities because it could be applied yearround to the registered crops. Additionally, the occupational inhalation POD is applicable to 

both durations; therefore the assessment is protective of both short- and intermediate-term 

exposures. Long-term exposures are not expected because exposures resulting from post-harvest 

uses are likely a series of short- or intermediate-term exposures, rather than continuous long-term 

exposure duration just to azoxystrobin. 

Exposure Time: The average occupational workday is assumed to be 8 hours. 

Occupational Post-application Non-Cancer Inhalation Risk Estimates

There are some occupational post-application inhalation risk estimates of concern for the 

registered post-harvest uses of azoxystrobin at baseline and maximum PPE mitigation. The LOC 

for occupational inhalation risk estimates is an MOE of 300. At baseline, occupational postapplication inhalation MOEs for the post-harvest uses of azoxystrobin ranged from 1.5 to 

5,200,000 for sorters/packers and from 32 to 1,200,000 for indirect inhalation exposures. 
Page 46 of 64

Table 8.3.1.1. Occupational Post-application Non-Cancer Exposure and Risk Estimates for Azoxystrobin

Crop/Site Activities

Max App. 

Rate

(% ai in 

solution)1

Inhalation Unit Exposure 

(μg/% ai)2

Inhalation Dose (mg/kg/day)3Inhalation MOE4(LOC = 300)

Baseline PF5 PF10 Baseline PF5 PF10 Baseline PF5 PF10

Citrus –

Concentrated 

Solution

Sorter

0.48

6720 1340 672 0.041 0.0081 0.0041 1.5 7.3 15

Packer 6760 1350 675 0.041 0.0081 0.0041 1.5 7.3 15

Citrus –

Diluted 

Solution

Sorter

0.12

6720 1340 672 0.0101 0.0020 0.0010 5.8 29 58

Packer 6760 1350 675 0.0101 0.0020 0.0010 5.8 29 58

Bananas

Sorter

0.01

6720 1340 672 0.0008 0.0002 0.0001 70 350 700

Packer 6760 1350 675 0.0008 0.0002 0.0001 70 350 700

Potato

Sorter 0.000013 6720 1340 672 0.000000011 0.0000000022 0.0000000011 5,200,000 26,000,000 52,000,000

Packer 0.000013 6760 1350 675 0.000000011 0.0000000022 0.0000000011 5,200,000 26,000,000 52,000,000

1. Used the highest ppm rate found on the registered labels (EPA Reg. No. 100-1093, 89442-21, 100-1098).

2. Based on Table 2 in ExpoSAC Policy/Guidance “Assessment of Occupational Exposure for Post-Harvest Commodity Pesticide Treatments” 

(M. Crowley, 23-MAR-2012); Level of mitigation: T-shirt/NG = t-shirt and no gloves; NR = no respirator.

3. Inhalation Dose = [Unit Exposure (μg/% ai) * Application Rate (% ai in solution) * Adjustment Factor (0.001 μg/mg)] ÷ Body Weight (80 

kg).

4. Inhalation MOE = Inhalation POD (0.059 mg/kg/day) ÷ Inhalation Dose.

Table 8.3.1.2. Occupational Post-application Non-Cancer Indirect Inhalation Exposure and Risk Estimates for Azoxystrobin.

Crop/Site

Max App. Rate

(% ai in 

solution)

Inhalation Unit Exposure (μg/% 

ai)1

Inhalation Dose

(mg/kg/day)2 MOE3

Baseline PF5 PF10 Baseline PF5 PF10 Baseline PF5 PF10

Citrus –

Concentrated 

Solution

0.49

307 61.4 30.7

0.0019 0.00037 0.00019 32 160 320

Citrus –

Diluted 

Solution 

0.12 0.00046 0.000093 0.000046 130 640 1,300

Bananas 0.04 0.000039 0.0000077 0.0000039 1,500 7,600 15,000

Potato 0.000013 0.000000050 0.000000010 0.0000000050 1,200,000 5,900,000 12,000,000

1. Based on Table 4 in ExpoSAC Policy/Guidance “Assessment of Occupational Exposure for Post-Harvest Commodity Pesticide Treatments” 

(M. Crowley, 23-MAR-2012); Level of mitigation: NR = no respirator.

2. Inhalation Dose = [Unit Exposure (μg/% ai) * Application Rate (% ai in solution) * Adjustment Factor (0.001 μg/mg)] ÷ Body Weight (80 

kg)].

3. Inhalation MOE = Inhalation POD (0.059 mg/kg/day)/Inhalation Dose.

8.3.2 Occupational Post-application Dermal Exposure/Risk Estimates

An occupational post-application dermal assessment was not completed for azoxystrobin on sod 

farms because no dermal hazard was identified in the toxicity database. 

Because no dermal hazard was identified for azoxystrobin, an occupational post-application 

assessment on agricultural crops were not conducted; therefore a DFR study is not required for 

azoxystrobin at this time. 

Restricted Entry Interval
Page 47 of 64

For Azoxystrobin Products with a >12 Hour REI

Azoxystrobin is classified as Toxicity Category III via the dermal route and Toxicity Category 

IV for skin irritation potential. It is not a skin sensitizer. There was no short- or intermediateterm dermal hazard identified for azoxystrobin. Under 40 CFR 156.208 (c) (2), ai’s classified as 

Acute III or IV for acute dermal, eye irritation and primary skin irritation are assigned a 12-hour 

REI. Therefore, the [156 subpart K] Worker Protection Statement interim REI of 12 hours is 

adequate to protect agricultural workers from post-application exposures to azoxystrobin. 

For Azoxystrobin Products with a 4-hour REI

Based on the acute toxicity categories, the Worker Protection Standard (WPS) REIs for

azoxystrobin, is 12-hours. REIs may be reduced from 12 hours if the registrant submitted 95-3 

package has been approved and certain criteria are met for both the technical material and the 

different end-use products in accordance with the Pesticide Registration (PR) Notice 95-3 

[Reduction of WPS Interim REIs for Certain Low Risk Pesticides]16. Based only on the acute 

toxicity categories for azoxystrobin, HED recommends a 12-hour REI.

 

16 Available: http://www2.epa.gov/pesticide-registration/prn-95-3-reduction-worker-protection-standard-wpsinterim-restricted-entry
Page 48 of 64

Appendix A. Summary of Occupational and Residential Non-cancer Algorithms

Residential Non-cancer Handler Algorithms

Turf, Gardens, Trees, Indoor Environments 

Inhalation Handler Exposure Algorithm

Daily inhalation exposure (mg/day) for residential pesticide handlers, for a given formulationapplication method combination, is estimated by multiplying the formulation-application 

method-specific unit exposure by an estimate of the amount of active ingredient handled in a 

day, using the equation below:

E = UE * AR * A

where:

E = exposure (mg/day);

UE = unit exposure (mg/lb ai);

AR = application rate (e.g., lb ai/ft2, lb ai/gal); and

A = area treated or amount handled (e.g., ft2/day, gal/day).

Treated Paints and Preservatives

Dermal and Inhalation Handler Exposure Algorithm

Daily dermal and inhalation exposure (mg/day) for residential pesticide handlers, for a given 

formulation-application method combination, is estimated by multiplying the formulationapplication method-specific unit exposure by an estimate of the amount of active ingredient 

handled in a day, using the equation below:

E = UE * AR * N

where:

E = exposure (mg/day);

UE = unit exposure (mg/lb ai);

AR = application rate (lb ai/gallon); and

A = amount of paint used per day (gallons/day).

Residential Handler Dose Calculations

Dermal and/or inhalation absorbed doses normalized to body weight are calculated as:

D = E *AF / BW

where:
Page 49 of 64

D = dose (mg/kg-day);

E = exposure (mg/day);

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

BW = body weight (kg).

Residential Non-cancer Post-application Algorithms

Post-application Hand-to-Mouth Exposure Algorithm– Physical Activities on Turf

Exposure from hand-to-mouth activity is calculated as follows (based on the algorithm utilized in 

the SHEDS-Multimedia model):

E = [HR * (FM * SAH) * (ET * N_Replen) * (1- (1- SE)

(Freq_HtM/N-Replen))]

where:

E = exposure (mg/day);

HR = hand residue loading (mg/cm2);

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

SAH = typical surface area of one hand (cm2);

ET = exposure time (hr/day);

N_Replen = number of replenishment intervals per hour (intervals/hour);

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

Freq_HtM = number of hand-to-mouth contacts events per hour (events/hour).

and

SA * 2

Fai *DE

HR

H

hands



where:

HR = hand residue loading (mg/cm2);

Faihands = fraction ai on hands compared to total surface residue from dermal transfer coefficient 

study (unitless);

DE = dermal exposure (mg); and

SAH = typical surface area of one hand (cm2).

Dose, normalized to body weight, is calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and
Page 50 of 64

BW = body weight (kg).

Table A-1: Turf (Physical Activities) – Inputs for Residential Post-application Hand-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

Faihands

Fraction of ai on hands 

from dermal transfer 

coefficient study

(unitless)

Liquid formulations 0.06

Granule formulations 0.027

DE Dermal exposure (mg) Calculated

SAH

Typical surface area of one hand (cm2), children 1 < 

2 years old 150

AR Application rate

(mass active ingredient per unit area)

0.99 lb ai/A (liquids)

0.95 lb ai/A (granules)

HR Residue available on the hands (mg/cm2) Calculated via (DE * Faihands)/SAH

FM

Fraction hand surface area mouthed

(fraction/event) 0.127

N_Replen Replenishment intervals per hour

(intervals/hr) 4

ET Exposure time 

(hrs/day) 1.5

SE Saliva extraction factor

(unitless) 0.48

Freq_HtM Hand-to-mouth events per hour

(events/hr) 13.9

BW Body Weight

(kg)

Children 1 < 2 years 

old 11

Post-application Object-to-Mouth Exposure Algorithm– Physical Activities on Turf

Exposure from object-to-mouth activity is calculated as follows (based on the algorithm utilized 

in SHEDS-Multimedia):

E = [OR* CF1 * SAMO * (ET * N_Replen) * (1- (1- SEO)

(Freq_OtM/N_Replen))]

where:

E = exposure (mg/day);

OR = chemical residue loading on the object on day “t” (ug/cm2);

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

SAMO = area of the object surface that is mouthed (cm2/event);

ET = exposure time (hr/day);

N_Replen = number of replenishment intervals per hour (intervals/hour);

SEO = saliva extraction factor (i.e., mouthing removal efficiency); and

Freq_OtM = number of object-to-mouth contact events per hour (events/hour).

and
Page 51 of 64

OR = AR * FO * CF2 * CF3

where:

OR = chemical residue loading on the object (μg/cm2);

AR = application rate (lbs ai/ft2or lb ai/acre);

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

CF2 = weight unit conversion factor (4.54 x 108 μg/lb); and

CF3 = area unit conversion factor (1.08 x 10-3ft2/cm2or 2.47 x 10-8acre/cm2).

Dose, normalized to body weight, is calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).

Table A-2: Turf (Physical Activities) – Inputs for Residential Post-application Object-to-Mouth 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate (to turf)

(mass active ingredient per unit area)

0.99 lb ai/A (liquids)

0.95 lb ai/A (granules)

FO Fraction of AR as OR following application 1 0.01

SAMO

Surface area of object mouthed 

(cm2/event) 10

N_Replen Replenishment intervals per hour (intervals/hour) 4

SEO

Saliva extraction factor

(fraction) 0.48

ET Exposure time 

(hours per day) 1.5

Freq_OtM Object-to-mouth events per hour (events/hr) 8.8

BW Body Weight (kg) Children 1 < 2 years old 11

1 This SOP assumes that all of the residue on the turf could be transferred to the object (e.g., object residue is 

equal to turf transferable residue).

Post-application Incidental Soil Ingestion Exposure Algorithm– Physical Activities on Turf

Exposure from incidental soil ingestion is calculated as follows:

E = SRt * SIgR * CF1

where:

E = exposure (mg/day);

SRt = soil residue on day "t" (μg/g);

SIgR = ingestion rate of soil (mg/day); and
Page 52 of 64

CF1 = weight unit conversion factor (1 x 10-6g/μg).

and

SRt = AR * FS * (1-FD)

t

* CF2 * CF3 * CF4

where:

SRt = soil residue on day "t" (μg/g);

AR = application rate (lbs ai/ft2or lb ai/acre);

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

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

T = post-application day on which exposure is being assessed;

CF2 = weight unit conversion factor (4.54 x 108 μg/lb);

CF3 = area unit conversion factor (1.08 x 10-3ft2/cm2 or 2.47 x 10-8acre/cm2); and

CF4 = soil volume to weight unit conversion factor (0.67 cm3/g soil).

Dose, normalized to body weight, are calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).

Table A-3: Turf (Physical Activities) – Inputs for Residential Post-application Incidental Soil Ingestion 

Exposure 

Algorithm 

Notation

Exposure Factor

(units) Point Estimate(s)

AR Application rate

(mass active ingredient per unit area)

0.99 lb ai/A (liquids)

0.95 lb ai/A (granules)

FS Fraction of AR available in uppermost 1 cm of soil

(unitless) 1

FD

Daily residue dissipation

(fraction) 0.1

SIgR Soil ingestion rate (mg/day) 50

BW Body weight (kg) Children 1 < 2 years old 11

Post-application Episodic Granule Ingestion Exposure Algorithm– Physical Activities on Turf

Exposure from incidental ingestion of pesticide pellets or granules is calculated as follows:

 E = GIgR* FD * CF1

where:

E = exposure (mg/day);
Page 53 of 64

GIgR = ingestion rate of dry pesticide formulation (g/day);

FD = fraction of ai in dry formulation (unitless); and

CF1 = weight unit conversion factor (1,000 mg/g).

Dose, normalized to body weight, are calculated as:

BW

E

D 

where:

D = dose (mg/kg-day);

E = exposure (mg/day); and

BW = body weight (kg).

Table A-X: Turf (Physical Activities) – Inputs for Residential Post-application Episodic Granule

Ingestion Exposure 

Algorithm 

Notation

Exposure Factor 

(units) Point Estimate(s)

FD Fraction of active ingredient in dry formulation 0.3% ai

AR Application rate (lbs/A or lbs/1,000 ft2) 0.95 lb ai/A (granules)

GIgR Granule ingestion rate per day

(g/day) 1 0.3

BW Body Weight (kg) Children 1 < 2 years old 11

1 See discussion below on how this value may be adjusted if product specific information is available.

Incidental Oral Exposure from Treated Vinyl Flooring

Residential Post-application Non-Cancer Exposure and Risk Equations

The following equations are used to calculate the surface residue (SR), hand residue (HR), 

exposure (E) and potential daily dose (PDD):

SR = D * VT * WF * AF

 

Where: 

SR = Surface Residue (mg/cm2)

D = Density of vinyl flooring (gm/cm3) 

VT = Vinyl flooring thickness (mm)

WF = Weight Fraction of a.i. in vinyl

AF = Availability Factor

HR = SR * FH

Where: 

HR = Hand Residue (mg/cm2)
Page 54 of 64

SR = Surface Residue (mg/cm2)

FH = Fraction ai transferred to hands

Exp = HR * FM * SAH * ET * NR * [1 – (1-SE)FHtM / NR]

Where:

Exp = Exposure (mg/day)

HR = Hand Residue (mg/cm2)

FM = Fraction hand surface area mouthed per event

SA = Surface area of one hand (cm2)

ET = Exposure time (hours/day)

NR = Number of replenishment intervals per hour

SE = Saliva extraction efficiency (%/100) 

FHtM = Number of hand-to-mouth contacts per hour

BW = Body weight (kg)

PDD = Exp / BW

Where: 

PDD = Potential daily dose (mg/kg/day)

Exp = Exposure (mg/day)

BW = Body weight (kg)

Assumptions used to Calculate SR and HR:

The following assumptions are for the calculation of the surface residue (SR) and hand residue 

(HR) values. 

 D: The vinyl density is 1.3 g/cm3 based on the density of polyvinyl chloride. 

 VT: The vinyl flooring is assumed to be 3 mm thick.

 WF1: The fraction of ai in the vinyl flooring is 0.225% based on the labels.

 AF: It is assumed that 0.5% of the azoxystrobin ai impregnated within the vinyl matrix is available at the 

surface of the flooring which is subsequently available for human exposure (standard AD assumption)

 FH: Since azoxystrobin data are not available from which a chemical specific transfer factor could be 

estimated, exposures are calculated using a transfer factor of 1.0, which assumes that all of the available 

residues are transferable. 

Assumptions used to Calculate Exposure

The following assumptions are for the use of the SHEDs model to calculate the exposure using 

the HR value calculated above. The SHEDs model assumptions are the same as those used by 

HED and are the recommended values from Table 9-7 of the HED Residential SOPs.

 FM: The fraction hand surface area mouthed per event is 0.13.

 SA: The surface area of one toddler hand is 150 cm2.

 NR: The number of replenishment intervals per hour is 4.

 ET: The exposure time is 2 hours/day for hard surface flooring. 

 SE: The saliva extraction fraction is 0.48. 

 FHtM = The Number of hand-to-mouth contacts per hour is 20. 

 BW: The body weight is 11.4 for children 1 <2 years old.
Page 55 of 64

Incidental Oral Exposure from Plastic Toys

The following equations are used to calculate the surface residue (SR), object residue (OR), 

exposure (E) and potential daily dose (PDD):

SR = WF x W x CF x F

 SA1

Where:

SR = Surface residue (mg ai/cm2)

WF = Weight fraction of ai in toy (% ai/100)

W = Weight of toy (g)

CF = Conversion factor (1,000 mg/g)

AF = Fraction additive available at the surface of the toy (%/100)

SA1 = Surface area of toy (cm2)

OR = SR * FH

Where: 

OR = Object Residue Loading (mg/cm2)

SR = Surface Residue (mg/cm2)

FO = Fraction available for transfer

Exp = OR * SAM * ET * NR * [1 – (1-SE)FOtM / NR]

Where:

Exp = Exposure (mg/day)

OR = Object Residue (mg/cm2)

SAM = Surface area mouthed (cm2)

ET = Exposure time (hours/day)

NR = Number of replenishment intervals per hour

SE = Saliva extraction efficiency (%/100) 

FHtM = Number of hand-to-mouth contacts per hour

BW = Body weight (kg)

PDD = Exp / BW

Where: 

PDD = Potential daily dose (mg/kg/day)

Exp = Exposure (mg/day)

BW = Body weight (kg)

Assumptions used to Calculate SR and OR:

The following assumptions are for the calculation of the surface residue (SR) and object residue 

(OR) values. 

 WF: The weight fraction is 0.00225 is based on the application rate of 0.225% a.i..

 W: The weight of a 500 cm2 toy is 50 grams, which is based on data showing that a polyethylene highchair 

sample has a density of 0.10 grams/cm2(AD standard assumption). 

 AF: It was assumed that 0.5% of the azoxystrobin impregnated within the plastic matrix is available at the 

surface of the toy which is subsequently available for human exposure (AD standard assumption). 
Page 56 of 64

 SA1: It is assumed that 500 cm2is a representative surface area of a plastic toy. 

Assumptions used to Calculate Exposure

The following assumptions are for the use of the SHEDs model to calculate the exposure using 

the HR value calculated above. The SHEDs model assumptions are the same as those used by 

HED and are the recommended values from Table 9-7 of the HED Residential SOPs.

 SAM: The surface area mouthed per event is 10 cm2.

 NR: The number of replenishment intervals per hour is 4.

 ET: The exposure time is 4 hours/day for mouthing objects indoors. 

 SE: The saliva extraction fraction is 0.48. 

 FHtM: The number of object-to-mouth contacts per hour is 14. 

 BW: The body weight is 11.4 for children 1 <2 years old.

Occupational Non-cancer Handler Algorithms

Potential daily exposures for occupational handlers are calculated using the following formulas:

E=UE * AR * A * 0.001 mg/ug

where:

E = exposure (mg ai/day),

UE = unit exposure (μg ai/lb ai),

AR = maximum application rate according to proposed label (lb ai A or lb ai/gal), and

A = area treated or amount handled (e.g., A/day, gal/day).

The daily doses are calculated using the following formula:

ADD= 

E * AF

BW

where:

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day),

E = exposure (mg ai/day),

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

BW = body weight (kg).

Margin of Exposure: Non-cancer risk estimates for each application handler scenario are 

calculated using an MOE, which is a ratio of the toxicological endpoint to the daily dose of 

concern. The daily dermal and inhalation dose received by occupational handlers are compared

to the appropriate POD (i.e., NOAEL) to assess the risk to occupational handlers for each 

exposure route. All MOE values are calculated using the following formula:
Page 57 of 64

MOE= 

POD

ADD

where:

MOE = margin of exposure: value used by HED to represent risk estimates (unitless),

POD = point of departure (mg/kg/day), and

ADD = average daily dose absorbed in a given scenario (mg ai/kg/day).
Page 58 of 64

Appendix B. TTR and DFR Data Requirements

Turf Transferable Residue (TTR): In accordance with 40CFR158, TTR data are required for all 

occupational (e.g., sod farms, golf courses, parks, and recreational areas) or residential turf uses

that could result in post-application exposure to turf. In the absence of chemical-specific TTR 

data, EPA uses default values. The 2012 Standard Operating Procedures for Residential 

Pesticide Exposure Assessment includes an analysis of all TTR data, available at the time, which 

resulted in the selection of revised liquid and granular default values for the fraction of the 

application rate available for transfer after a turf application (FAR). These values are based on an 

analysis of 59 TTR studies performed with the Modified California Roller Method (36 studies 

using liquids, 11 studies using wettable powders/water dispersible granules, and 12 studies using 

granules). The liquid results (N=131) indicate a range of FAR values from 0.0005% to 6.1% and 

the granular results (N=37) indicate a range of 0.00064% to 0.69%. In both the liquid and 

granular data, a large range of transferability is observed and this variability can potentially be 

attributable to many factors such as active ingredient; formulation; field conditions in the studies; 

weather conditions (e.g., humidity); or many other difficult to quantify factors. Although 

witnessed across multiple chemicals, this range in FAR values is not expected when considering 

TTR data for a single chemical. HED selected 1% and 0.2% as high-end default values for 

liquid and granular products, respectively. Because TTR data are not available for azoxystrobin, 

EPA is using the default values for liquid and granular products. Although there may be a small 

degree of uncertainty in the use of the default TTR value for azoxystrobin (i.e., there is a small 

chance that the FAR value may exceed the applicable default value), it is likely that the healthprotective aspects of EPA’s residential post-application turf assessment methodology will more 

than compensate for this potential uncertainty (i.e., the methodology is likely to overestimate 

exposure by a factor greater than the factor than the highest measured FAR values exceed the 

defaults ). For example, when assessing residential post-application turf exposure, EPA 

assumes the following: exposures occur to zero-day (i.e., day of application ) residues every 

day of the assessed exposure duration (i.e., EPA assumes that no dissipation or degradation 

occurs, it doesn’t rain, the grass is not mowed, etc); individuals perform the same postapplication activities performed in the turf transfer coefficient study day after day (e.g., 

tumbling, playing on turf with toys, etc.); and individuals engage in these post-application 

activities for a high-end amount of time every day that is represented by data reflecting time 

children spend outdoors and not specifically engaged in activities on turf, when in actuality 

children do not spend all of their outdoor time on turf and high-end levels of activity will not 

occur every day.

Given the conservatisms discussed above and the potential compounding nature of these 

conservatisms, EPA is able to rely upon the calculated exposure estimates with confidence that 

exposure is not being underestimated. 

Since the estimated residential turf post-application exposure for residential turf using default 

TTR values for azoxystrobin is minimal in comparison to the level of concern (i.e., the calculated 

MOE is greater than 10 times higher than the level of concern, MOE = 2,300 compared to the 

LOC of 100); EPA is waiving the 40CFR TTR data requirement. In this instance, it is unlikely 

that chemical-specific TTR data would be needed to further refine exposure assessments or 
Page 59 of 64

would add appreciably to our general understanding of the availability of turf transferable 

pesticide residues.

An occupational post-application dermal assessment was not completed for azoxystrobin on sod 

farms because no dermal hazard was identified in the toxicity database. Therefore, a TTR study 

on turf is not required at this time. 

Dislodgeable Foliar Residue (DFR): In accordance with 40CFR158, DFR data are required for 

all occupational (e.g., crop, nursery, greenhouse use sites) or residential (e.g., ornamental and 

vegetable gardens, pick your own farms, retail tree farms) uses that could result in postapplication exposure to foliage. In the absence of chemical-specific DFR data, EPA uses default 

values. The 2012 Standard Operating Procedures for Residential Pesticide Exposure 

Assessment includes an analysis of a number of DFR studies, which resulted in the selection of a 

revised default values for the fraction of the application rate available for transfer after a foliar 

application (FAR). These values are based on an analysis of 19 DFR studies. Since that time, the 

Agricultural Re-entry Task Force has submitted information (MRID 49299201) that corrects an 

application rate error made in the original submission of “ARF039 – Determination of Dermal 

and Inhalation Exposure to Reentry Workers During Chrysanthemum Pinching in a Greenhouse” 

(EPA MRID 45344501). As a result, the range of FAR values was revised from 2% - 89% to 2% 

- 47%. In the data, a large range of transferability is observed and this variability can potentially 

be attributable to many factors such as active ingredient; formulation; field conditions in the 

studies; weather conditions (e.g., humidity); or many other difficult to quantify factors. 

Although witnessed across multiple chemicals, this range in FAR values is not expected when 

considering DFR data for a single chemical. At this time, the ARTF submission did not alter the 

selection of 25% as the reasonable, high-end default value. Because no dermal hazard was 

identified for azoxystrobin, a residential post-application assessment on ornamentals and an 

occupational post-application assessment on agricultural crops were not conducted; therefore a 

DFR study is not required for azoxystrobin at this time. 
Page 60 of 64

Appendix C. Exposure Inputs and Inhalation Doses for Registered Conventional Uses of Azoxystrobin. 

Table C.1. Occupational Handler Non-Cancer Exposure Inputs and Inhalation Doses for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1

Area 

Treated/Amount 

Handed

Inhalation Unit Exposure (ug/lb ai) Inhalation Dose (mg/kg/day)

Baseline PF5 PF10 EC Baseline PF5 PF10 EC

Mixer/Loader

Mixing/Loading Dry 

Flowables for Aerial 

Application

Nursery Ornamentals 60 Acres 8.96 1.795 0.896 0.24 0.00168 0.000336 0.000168 0.000045

Orchards/Vineyards 350 Acres 8.96 1.795 0.896 0.24 0.0098 0.00196 0.00098 0.000263

Sod 350 Acres 8.96 1.795 0.896 0.24 0.0373 0.00745 0.00373 0.000998

Field Crop, Typical 350 Acres 8.96 1.795 0.896 0.24 0.0129 0.00259 0.00129 0.000346

Field Crop, High Acreage 1200 Acres 8.96 1.795 0.896 0.24 0.0538 0.0108 0.00538 0.00144

Mixing/Loading Dry 

Flowables for Airblast 

Application

Nursery Ornamentals 20 Acres 8.96 1.795 0.896 0.24 0.00056 0.000112 0.000056 0.000015

Orchards/Vineyards 40 Acres 8.96 1.795 0.896 0.24 0.00112 0.000224 0.000112 0.000030

Mixing/Loading Dry 

Flowables for Chemigation 

Application

Orchards/Vineyards 350 Acres 8.96 1.795 0.896 0.24 0.0098 0.00196 0.00098 0.000263

Sod 350 Acres 8.96 1.795 0.896 0.24 0.0373 0.00745 0.00373 0.000998

Field Crop, Typical 350 Acres 8.96 1.795 0.896 0.24 0.0129 0.00259 0.00129 0.000346

Field Crop, High Acreage 350 Acres 8.96 1.795 0.896 0.24 0.0156 0.00314 0.00156 0.00042

Nursery Ornamentals 60 Acres 8.96 1.795 0.896 0.24 0.00168 0.000336 0.000168 0.000045

Mixing/Loading Dry 

Flowables for Groundboom 

Application

Golf course (tees and greens) 5 Acres 8.96 1.795 0.896 0.24 0.000533 0.000106 0.0000533 0.0000143

Golf course (fairways, tees, and 

greens)

40 Acres 8.96 1.795 0.896 0.24 0.00425 0.000851 0.000425 0.000114

Field-Grown Ornamental Crops 40 Acres 8.96 1.795 0.896 0.24 0.00112 0.000224 0.000112 0.000030

Nursery Ornamentals 60 Acres 8.96 1.795 0.896 0.24 0.00168 0.000336 0.000168 0.000045

Sod 80 Acres 8.96 1.795 0.896 0.24 0.00851 0.0017 0.000851 0.000228

Orchards/Vineyards 40 Acres 8.96 1.795 0.896 0.24 0.00112 0.000224 0.000112 0.00003

Field Crop, Typical 80 Acres 8.96 1.795 0.896 0.24 0.00296 0.000591 0.000296 0.0000793

Field Crop, High Acreage 200 Acres 8.96 1.795 0.896 0.24 0.00896 0.00179 0.000896 0.00024

Mixing/Loading Granules for 

Aerial Application

Sod 350 Acres 1.7 0.34 0.17 0.083 0.00706 0.00141 0.000706 0.000345

Mixing/Loading Granules for 

Tractor-Drawn Spreader 

Applications

Golf Course (Fairways, Tees, 

Greens)

40 Acres 1.7 0.34 0.17 0.083 0.000808 0.000161 0.00008088 0.0000394

Golf Course (Tees and Greens) 5 Acres 1.7 0.34 0.17 0.083 0.000101 0.0000203 0.0000101 0.00000493

Sod 80 Acres 1.7 0.34 0.17 0.083 0.00161 0.000323 0.000161 0.00007895

Mixing/Loading Liquids for 

Aerial Application

Nursery Ornamentals 60 Acres 0.219 0.0438 0.0219 0.083 0.0000411 0.00000821 0.00000411 0.0000156

Orchards/Vineyards 350 Acres 0.219 0.0438 0.0219 0.083 0.00024 0.0000479 0.000024 0.0000908
Page 61 of 64

Table C.1. Occupational Handler Non-Cancer Exposure Inputs and Inhalation Doses for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1

Area 

Treated/Amount 

Handed

Inhalation Unit Exposure (ug/lb ai) Inhalation Dose (mg/kg/day)

Baseline PF5 PF10 EC Baseline PF5 PF10 EC

Sod 350 Acres 0.219 0.0438 0.0219 0.083 0.000949 0.00019 0.0000949 0.00036

Field Crop, Typical 350 Acres 0.219 0.0438 0.0219 0.083 0.000316 0.0000633 0.0000316 0.00012

Field Crop, High Acreage 1200 Acres 0.219 0.0438 0.0219 0.083 0.00131 0.000263 0.000131 0.000498

Mixing/Loading Liquids for

Airblast Application

Nursery Ornamentals 20 Acres 0.219 0.0438 0.0219 0.083 0.0000138 0.00000274 0.00000138 0.00000519

Orchards/Vineyards 40 Acres 0.219 0.0438 0.0219 0.083 0.0000274 0.00000548 0.00000274 0.0000104

Mixing/Loading Liquids for 

Chemigation Application

Orchards/Vineyards 350 Acres 0.219 0.0438 0.0219 0.083 0.00024 0.0000479 0.000024 0.0000908

Sod 350 Acres 0.219 0.0438 0.0219 0.083 0.000949 0.00019 0.0000949 0.00036

Field Crop, Typical 350 Acres 0.219 0.0438 0.0219 0.083 0.000316 0.0000633 0.0000316 0.00012

Field Crop, High Acreage 350 Acres 0.219 0.0438 0.0219 0.083 0.000384 0.0000766 0.0000384 0.000145

Greenhouse Ornamentals 60 Acres 0.219 0.0438 0.0219 0.083 0.0000428 0.00000854 0.00000428 0.0000161

Nursery Ornamentals 60 Acres 0.219 0.0438 0.0219 0.083 0.0000411 0.00000821 0.00000411 0.0000156

Mixing/Loading Liquids for 

Groundboom Application

Golf Course (Tees and Greens) 5 Acres 0.219 0.0438 0.0219 0.083 0.0000135 0.00000271 0.00000135 0.00000514

Golf Course (Fairways, Tees, 

Greens)

40 Acres 0.219 0.0438 0.0219 0.083 0.000108 0.0000216 0.0000108 0.0000411

Field-Grown Ornamentals 40 Acres 0.219 0.0438 0.0219 0.083 0.0000274 0.00000548 0.00000274 0.0000104

Nursery Ornamentals 60 Acres 0.219 0.0438 0.0219 0.083 0.0000411 0.00000821 0.00000411 0.0000156

Greenhouse Ornamentals 60 Acres 0.219 0.0438 0.0219 0.083 0.0000428 0.00000854 0.00000428 0.0000161

Sod 80 Acres 0.219 0.0438 0.0219 0.083 0.000216 0.0000434 0.0000216 0.0000821

Orchards/Vineyards 40 Acres 0.219 0.0438 0.0219 0.083 0.0000274 0.00000548 0.00000274 0.0000104

Field Crop, Typical 80 Acres 0.219 0.0438 0.0219 0.083 0.0000723 0.0000145 0.00000723 0.0000274

Field Crop, High Acreage 200 Acres 0.219 0.0438 0.0219 0.083 0.000219 0.0000438 0.0000219 0.000083

Applicator

Applying Sprays with Aerial 

Application Equipment

Nursery Ornamentals 60 Acres

N/A

0.0049

N/A

0.000000919

Orchards/Vineyards 350 Acres 0.0049 0.00000536

Sod 350 Acres 0.0049 0.0000213

Field Crop, Typical 350 Acres 0.0049 0.00000708

Field Crop, High Acreage 1200 Acres 0.0049 0.0000294

Applying Sprays with 

Airblast Application 

Equipment

Nursery Ornamentals 20 Acres 4.71 0.942 0.471 0.068 0.000295 0.0000589 0.0000295 0.00000425

Orchards/Vineyards 40 Acres 4.71 0.942 0.471 0.068 0.000589 0.000118 0.0000589 0.0000085

Applying Sprays with Golf Course (Tees and Greens) 5 Acres 0.34 0.068 0.034 0.043 0.000021 0.00000421 0.0000021 0.00000266
Page 62 of 64

Table C.1. Occupational Handler Non-Cancer Exposure Inputs and Inhalation Doses for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1

Area 

Treated/Amount 

Handed

Inhalation Unit Exposure (ug/lb ai) Inhalation Dose (mg/kg/day)

Baseline PF5 PF10 EC Baseline PF5 PF10 EC

Groundboom Application 

Equipment

Golf Course (Fairways, Tees, 

Greens)

40 Acres 0.34 0.068 0.034 0.043 0.000169 0.0000336 0.0000169 0.0000213

Field-Grown Ornamentals 40 Acres 0.34 0.068 0.034 0.043 0.0000425 0.0000085 0.00000425 0.00000538

Nursery Ornamentals 60 Acres 0.34 0.068 0.034 0.043 0.0000638 0.0000128 0.00000638 0.00000806

Greenhouse Ornamentals 60 Acres 0.34 0.068 0.034 0.043 0.0000663 0.0000133 0.00000663 0.00000839

Sod 80 Acres 0.34 0.068 0.034 0.043 0.000336 0.0000674 0.0000336 0.0000426

Orchards/Vineyards 40 Acres 0.34 0.068 0.034 0.043 0.0000425 0.0000085 0.00000425 0.00000538

Field Crop, Typical 80 Acres 0.34 0.068 0.034 0.043 0.000112 0.0000225 0.0000112 0.0000143

Field Crop, High Acreage 200 Acres 0.34 0.068 0.034 0.043 0.00034 0.000068 0.000034 0.000043

Applying Granules with 

Aerial Application Equipment Sod 350 Acres N/A 1.3 N/A 0.0054

Applying Granules with a 

Tractor-Drawn Spreader

Golf Course (Fairways, Tees, 

Greens) 40 Acres 1.2 0.24 0.12 0.22 0.00057 0.000114 0.000057 0.000105

Golf Course (Tees and Greens) 5 Acres 1.2 0.24 0.12 0.22 0.0000713 0.0000143 0.00000713 0.0000131

Sod 80 Acres 1.2 0.24 0.12 0.22 0.00114 0.000228 0.000114 0.000209

Flagger

Flagging for Aerial 

Applications (Sprays) Sod 350 Acres 0.35 0.07 0.035 N/A 0.00145 0.000291 0.000145 N/A

Flagging for Aerial 

Applications (Granules) Sod 350 Acres 0.15 0.03 0.015 N/A 0.000624 0.000125 0.0000624 N/A

Mixer/Loader/Applicator

Mixing/Loading/Applying 

Dry Flowable or Liquid 

Formulations with Backpack 

Sprayer

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals 

(Ground Directed)

40 gal 2.58 0.516 0.258 N/A 0.0000323 0.00000645 0.00000323 N/A

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals 

(Broadcast)

40 gal 69.1 13.8 6.9

N/A

0.000864 0.000173 0.0000863

N/A Landscaping (Plants, Flowers, 

Trees, Turf) (Broadcast Treatment) 40 gal 69.1 13.8 6.9 0.00411 0.000821 0.00041

Landscaping Turf (Spot Treatment) 40 gal 2.58 0.516 0.258 0.000154 0.0000308 0.0000154

Mixing/Loading/Applying 

Dry Flowable or Liquid 

Formulations with a Manually 

Pressurized Handwand

Christmas Tree Farm, Nursery 

Ornamentals (Broadcast) 40 gal 30 6 3

N/A

0.000375 0.000075 0.0000375

N/A

Landscaping (Plants, Flowers, 

Trees, Turf) 40 gal 30 6 3 0.00179 0.000358 0.000179
Page 63 of 64

Table C.1. Occupational Handler Non-Cancer Exposure Inputs and Inhalation Doses for the Registered Conventional Uses of Azoxystrobin1.

Exposure Scenario Crop or Target1

Area 

Treated/Amount 

Handed

Inhalation Unit Exposure (ug/lb ai) Inhalation Dose (mg/kg/day)

Baseline PF5 PF10 EC Baseline PF5 PF10 EC

Mixing/Loading/Applying 

Dry Flowable Formulations 

with a Mechanically 

Pressurized Handwand

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals 1000 gal 8.68 1.74 0.87

N/A

0.00271 0.000544 0.000273 N/A

Golf Course (Tees, Greens, 

Fairways) 5 Acres 42 8.4 4.2 0.0025 0.000499 0.00025 N/A

Landscaping (Trees, Shrubs, 

Bushes) 1000 gal 8.68 1.74 0.87 0.0129 0.00259 0.0013 N/A

Field Crop, Typical 1000 gal 8.68 1.74 0.87 0.00358 0.000718 0.000359 N/A

Mixing/Loading/Applying 

Liquids with a Manually 

Pressurized Handwand

Greenhouse Ornamentals 40 gal 30 6 3 N/A 0.00039 0.000078 0.000039 N/A

Mixing/Loading/Applying 

Liquids with a Mechanically 

Pressurized Handwand

Orchard/Vineyard, Christmas Tree 

Farm, Nursery Ornamentals 1000 gal 8.68 1.74 0.87

N/A

0.00271 0.000544 0.000273 N/A

Greenhouse Ornamentals 1000 gal 120 24 12 0.0255 0.0051 0.00255 N/A

Golf Course (Tees, Greens, 

Fairways), Landscaping Turf, 5 Acres 1.9 0.38 0.19 0.00000119 0.00000023

8

0.000000119 N/A

Landscaping (Trees, Shrubs 

Bushes) 1000 gal 8.68 1.74 0.87 0.0013 0.0013 0.0013 N/A

Field Crop, Typical 1000 gal 8.68 1.74 0.87 0.00358 0.000718 0.000359 N/A

Loading/Applying Granule

Formulations with a Rotary 

Spreader

Golf Course (Fairways, Tees, 

Greens) 5 Acres 10 2 1 N/A 0.000594 0.000119 0.0000594 N/A

Table C.2. Occupational Handler Inputs and Inhalation Doses for the Registered Post-Harvest Uses of Azoxystrobin.

Exposure Scenario Crop or Target

Amount ai 

Handled Inhalation Unit Exposure (μg/lb ai) Inhalation Dose (mg/kg/day)3

gal solution Baseline5 PF5 PF10 Baseline5 PF5 PF10

Mixing/Loading For Post-Harvest 

Treatment in a Closed Automated System

Citrus 25,000 0.083 N/A N/A 0.0039 N/A N/A

Potatoes 25,000 0.083 N/A N/A 0.00000013 N/A N/A

Bananas 25,000 0.083 N/A N/A 0.0000089 N/A N/A

Mixing/Loading Dry Flowable 

Formulations in an Automated System Bananas 25,000 8.96 1.792 0.896 0.00096 0.00019 0.00096

Mixing/Loading Liquids in an Automated 

System Citrus 25,000 0.219 0.0438 0.0219 0.0103 0.0021 0.00103
Page 64 of 64

Table C.2. Occupational Handler Inputs and Inhalation Doses for the Registered Post-Harvest Uses of Azoxystrobin.

Exposure Scenario Crop or Target

Amount ai 

Handled Inhalation Unit Exposure (μg/lb ai) Inhalation Dose (mg/kg/day)3

gal solution Baseline5 PF5 PF10 Baseline5 PF5 PF10

Bananas2 25,000 0.219 0.0438 0.0219 0.000024 0.0000047 0.0000024

Applying Direct Post-Harvest Sprays with 

a Mechanically Pressurized Handgun

Citrus 25,000 3.9 0.78 0.39 0.18 0.037 0.018

Bananas2 25,000 3.9 0.78 0.39 0.00042 0.000084 0.000042

1 Based on registered labels (Reg. No. 89442-21, 100-1098, 100-1093).

2 Based on ExpoSAC Post-Harvest Policy. 

3 Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/ gal) × Area Treated or Amount Handled Daily (gal/day) ÷ BW (80 kg).

4 Inhalation MOE = Inhalation NOAEL (mg/kg/day) ÷ Inhalation Dose (mg/kg/day). Shaded MOEs indicated MOEs of concern (LOC = 300).

5 For closed automated system, baseline exposures represent engineering control protection. “Baseline” for all other scenarios represents no respirator.