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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY AND

POLLUTION PREVENTION

DATE: November 30, 2011

MEMORANDUM

SUBJECT: Amicarbazone: Occupational and Residential Exposure Assessment for Proposed 

Uses on Turf, Christmas Tree Farms, Non-Crop Areas and on Conifers in 

Nurseries.

PC Code: 114004 DP Barcode: D394924

Decision No.: 441345 Registration Nos.: 66330-46

Petition Nos: NA Regulatory Action: Section 3 Registration

Assessment Type: Occupational/Residential Case No.: NA

TXR No.: NA CAS Number: 129909-90-6

MRID: NA 40 CFR: 180.615

FROM: Zaida Figueroa, Industrial Hygienist

Risk Assessment Branch (RAB) II

Health Effects Division (7509P)

THROUGH: Richard A. Loranger, Ph.D., Branch Senior Scientist

Risk Assessment Branch (RAB) II 

Health Effects Division (7509P)

TO: Michael Walsh/Kathryn Montague, RM Team 23

Herbicide Branch

Registration Division (7505P)

Action Requested:

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

exposure and risk assessment for proposed uses of the herbicide amicarbazone to control 

broadleaf weeds in residential and commercial lawns, golf course, sod farms, recreational turf, 

non-crop areas, Christmas tree farms and conifers in nurseries. The proposed use pattern results 

in the first residential use for the active ingredient. Note: This memorandum was reviewed by 

the Exposure Science Advisory Committee (ExpoSAC) on October 20, 2011. 
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1.0 Executive Summary

Amicarbazone, 4-amino-4,5-dihydro-N-(1,1-dimethylethyl)-3-(1-methylethyl)-5-oxo-1H-1,2,4-

triazole-1-carboxamide, is a triazolinone herbicide related to carfentrazone, flucarbazone, 

propoxycarbazone, and sulfentrazone. A Section 3 registration of a dry flowable formulation is 

requested by Arysta LifeScience North America, LLC for use on turf (lawns, golf course, sod 

farms, recreational turf), ornamentals, non-crop areas, Christmas tree farms and conifers in 

nurseries. Application timing includes pre-emergence and early post-emergence to control 

broadleaf weeds. Amicarbazone may be applied through a variety of application methods 

including ground equipment, backpack, and hand held equipment.

This assessment addresses exposure and risk associated with the proposed end-use product for 

amicarbazone when used as directed by commercial applicators as well as residential 

homeowners. There is a potential for short- and intermediate-term occupational exposure 

associated with handler activities (mixing, loading, and applying) as well as with 

postapplication activities (i.e., re-entering treated areas). There is also a potential for shortterm residential exposure to amicarbazone during handling (mixing, loading, and applying), 

and postapplication activities. Chronic exposure is not expected for the proposed use patterns.

Hazard Characterization

The toxicology database is complete and adequate for purposes of this risk assessment. 

Amicarbazone exhibits low acute toxicity. The available database indicates that the major 

effects in mammals are general toxicity, as evidenced by decreased body weight and weight gain, 

and liver toxicity. The mutagenicity battery for this chemical is complete and indicates that 

amicarbazone is not a mutagen. Amicarbazone has been classified as “not likely to be a human 

carcinogen”. Although the acute neurotoxicity study in rats showed signs of neurotoxicity, no 

such effects were seen in the subchronic and developmental neurotoxicity studies. 

In the previous risk assessment for amicarbazone (K. Kosick, 8/10/2005, D288216), HED 

concluded there was no dermal endpoint based on the lack of systemic toxicity or local dermal 

irritation from a 21-day dermal toxicity study in the rat. Using a ratio of the LOAELs from 

several oral studies in the rat to the NOAEL from the 21-day dermal rat study (1000 mg/kg/day), 

a conservative dermal absorption factor of less than 5% was estimated. Therefore, dermal 

absorption is not considered to be a major route of uptake for this chemical and the dermal route 

of exposure was not considered for this risk assessment. In the absence of a route-specific study

for inhalation, HED selected an endpoint from the 90-day dog study for the inhalation exposure 

and risk assessment. There were numerous effects observed at the LOAEL of 25 mg/kg/day

(thyroid, liver, gall bladder, and blood); the NOAEL of 6.28 mg/kg/day was selected as the point 

of departure for inhalation risk assessment. Since no inhalation toxicity data are available, 

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

exposure. 

For the current risk assessment, HED selected an endpoint for the purpose of assessing children’s 

incidental oral exposure on treated turf. Only short-term (1-30 days) durations are relevant for 

this route of exposure. The same subchronic oral toxicity study in the dog used for assessing 

inhalation exposure and risk was selected for assessing incidental oral exposure.
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FQPA and Uncertainty Factors

The database is complete with respect to pre- and post-natal toxicity and shows no evidence of 

increased qualitative or quantitative susceptibility. Although neurotoxicity was observed with 

exposure to amicarbazone in adult animals in gavage studies, no neurotoxic effects were 

observed in offspring at dose levels that resulted in general systemic toxicity. Potential 

immunotoxic effects were observed in the chronic dog and rat immunotoxicity studies only at 

doses greater than those selected for risk assessment and are therefore not of concern. HED 

recommends that the special 10X FQPA safety factor be reduced to 1X. No other database 

uncertainty factors are needed. The combined uncertainty factors of 100X (10X for intraspecies 

variability and 10X for interspecies extrapolation) serve as the level of concern (LOC) for 

occupational and residential exposure and risk. Margins of exposure (MOEs) greater than 100 

are not of concern.

Residential Handler Exposure

A dermal exposure assessment was not performed for residential handlers because no dermal 

endpoints were selected. Inhalation MOEs for handlers were significantly greater than the LOC 

of 100 (ranging from 3,600 to 220,000) and are not of concern.

Residential Postapplication Exposure

In the absence of a dermal endpoint, oral non-dietary ingestion exposures were assessed for 

children (i.e. soil ingestion, and hand-/object-to-mouth). The postapplication scenarios resulting 

from commercial and residential applications were assessed using the HED Draft Standard 

Operating Procedures (SOP’s) for Residential Exposure Assessments, 2000. Short-term hand-tomouth (HTM), object-to-mouth (OTM) and soil ingestion scenarios resulted in MOEs ranging 

from 910 to 270,000, and are not of concern. 

Since the proposed uses of amicarbazone are applied only in outdoor settings and amicarbazone

has a low vapor pressure (2.3 x 10-8 mm Hg), postapplication residential inhalation exposure and 

risk estimates were not quantitatively assessed. 

Summary of Residential Exposure

HED combines risk values resulting from separate exposure scenarios when it is likely they can 

occur simultaneously based on the use pattern and the behavior associated with the exposed 

population. However, since a dermal endpoint was not selected, the only relevant route of 

exposure for adults is through the inhalation route. Therefore, an adult combined residential 

exposure assessment was not conducted. Similarly, the only relevant route of exposure for 

children was through the oral route, and therefore a combined residential exposure assessment 

was not conducted for children. 

Occupational Handler Exposure

It is the policy of HED to use the best available data to assess handler exposure. Sources of 

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

Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1), the Agricultural Handler 

Exposure Task Force (AHETF) database, the Outdoor Residential Exposure Task Force 

(ORETF) database, or other registrant-submitted occupational exposure studies. Some of these 
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data are proprietary (e.g., AHETF data, MRID No. 44339801), and subject to the data protection 

provisions of FIFRA. Default assumptions established by the Health Effects Division (HED) 

Science Advisory Council for Exposure were used for parameters such as body weight, acres 

treated and amount handled. All occupational handler scenarios resulted in MOEs greater than 

the level of concern at the baseline PPE level of protection (i.e. single layer clothing and no 

respirator).

Occupational Postapplication Exposure

In the absence of a dermal endpoint, a dermal postapplication exposure assessment was not 

conducted. Furthermore, since the proposed uses of amicarbazone are in outdoor settings where 

postapplication inhalation exposures are expected to be minimal, and because amicarbazone has 

a low vapor pressure (2.3 x 10-8 mm Hg), handler inhalation exposure estimates are considered to 

be protective of occupational postapplication inhalation exposure scenarios.

Restricted Entry Interval

The restricted entry interval (REI) listed on proposed labels is based on the acute toxicity of the 

technical material. Amicarbazone exhibits low acute toxicity and is classified as Toxicity

Category III for eye irritation and Category IV for acute dermal and dermal irritation. It is not a 

dermal sensitizer. Acute toxicity Category III and IV chemicals require a 12-hour REI. 

Therefore, the 12-hour REI which appears on the proposed labels is considered appropriate. 

Review of Human Research

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

intentionally exposed to a pesticide or other chemical. These data, which include studies from 

the Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1); the Agricultural Handler 

Exposure Task Force (AHETF) database; and the Outdoor Residential Exposure Task Force 

(ORETF) database; are subject to ethics review pursuant to 40 CFR 26, have received that 

review, and are compliant with applicable ethics requirements. For certain studies that review 

may have included review by the Human Studies Review Board. Descriptions of data sources as 

well as guidance on their use can be found at http://www.epa.gov/pesticides/science/handlerexposure-data.html and http://www.epa.gov/pesticides/science/post-app-exposure-data.html.

Label Recommendations

The Registration Division (RD) should ensure the final label does not include the potential 

for application to Christmas trees using a mechanically pressurized handgun. No other 

recommendations are needed based on HED’s residential exposure and risk assessment.

2.0. Hazard Characterization

Amicarbazone is a triazolinone herbicide which controls broadleaf weeds by selective inhibition 

of acetolactase synthase, an enzyme involved in photosystem II in plants. The available database 

indicates that the major effects in mammals are general toxicity, as evidenced by decreased body

weight and weight gain, and liver toxicity. Decreased body weight and weight gain were 

observed in studies with rats, mice and rabbits and were the most sensitive toxicological 
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endpoints observed in many of the studies. In the chronic dog and subchronic rat and dog 

studies, liver effects were seen; including increased absolute and relative liver weights, slight 

liver hypertrophy, dilation of sinusoids and increased liver enzymes and cholesterol/triglycerides.

2.1 Hazard Profile

The toxicology database is complete and adequate for risk assessment. Amicarbazone exhibits 

low acute toxicity. The available database indicates that the major effects in mammals are 

general toxicity, as evidenced by decreased body weight and weight gain, and liver toxicity. The 

mutagenicity battery for this chemical is complete and indicates that amicarbazone is not a 

mutagen. Amicarbazone has been classified as “not likely to be a human carcinogen”. Although 

the acute neurotoxicity study in rats showed signs of neurotoxicity, no such effects were seen in 

the subchronic and developmental neurotoxicity studies. 

No dermal endpoint was selected for risk assessment, based on the lack of systemic toxicity or 

local dermal irritation in a 21-day dermal toxicity study in the rat. Using a ratio of the LOAELs 

from several oral studies in the rat to the NOAEL from the 21-day dermal rat study (1000 

mg/kg/day), a conservative dermal absorption factor of less than 5% was estimated. Therefore, 

dermal absorption is not considered to be a major route of exposure for this chemical and the 

dermal route of exposure was not considered for this risk assessment. There was no routespecific inhalation toxicity study available for endpoint selection. Therefore, for short-term (1-

30 days) and intermediate-term (1-6 months) inhalation risk assessment, the endpoint was 

selected from a dog subchronic oral toxicity study in which numerous toxic effects were 

observed at the LOAEL of 25 mg/kg/day. These effects included thyroid, liver, gall bladder and 

blood toxicity. The NOAEL for the study was 6.28 mg/kg/day, which served as the point of 

departure for risk assessment. For extrapolation from oral to inhalation exposure, toxicity via the 

inhalation route was assumed to be equivalent to toxicity via the oral route.

2.2 FQPA and Uncertainty Factor Considerations

HED has recommended the 10x FQPA factor be reduced to 1x. No evidence of increased 

quantitative or qualitative susceptibility was observed in the rat and rabbit developmental 

toxicity, rat reproductive toxicity or the rat developmental neurotoxicity studies. Although 

neurotoxicity was observed with exposure to amicarbazone in adult animals in gavage studies, no 

neurotoxic effects were observed in offspring in the rat developmental neurotoxicity study at 

dose levels that resulted in general systemic toxicity (decreased offspring and maternal body 

weight). Potential immunotoxic effects (chronic dog and rat immunotoxicity studies) were 

observed only at doses greater than those selected for risk assessment purposes and are therefore 

not of concern.

Given the completeness of the database, there are no database uncertainty factors to be retained 

during risk assessment, and therefore the level of concern (LOC) is a margin of exposure (MOE) 

of 100, based on the combined uncertainty factors of 100X (10X for interspecies extrapolation 

and 10X for intraspecies variability). MOEs greater than the LOC of 100 are not of concern.
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Table 1. Acute Toxicity Profile for Amicarbazone. 

Guideline 

No.

Study Type MRID(s) Results Tox Category

870.1100 Acute oral - Wistar rats 45121504 Males LD50 > 2050 

mg/kg

Females LD50 = 1015 

mg/kg

III

870.1200 Acute dermal - Wistar rats 45121503 LD50 > 5000 mg/kg IV

870.1300 Acute inhalation - Wistar rats 45121506 LC50 > 2.030 mg/L IV

70.2400 Acute eye irritation - New 

Zealand white rabbit

45121510 Eye irritation was 

present (including 

corneal opacity) at 24 

hours, but had cleared by 

day 7.

III

870.2500 Acute dermal irritation - New 

Zealand white rabbit

45121509 Primary irritation indices 

were 0

IV

870.2600 Skin sensitization - Hartley 

guinea pig

45121628

45121505

All scores during 

induction and challenge 

periods were 0.

Not a dermal 

sensitizer

Table 2. Summary of Toxicological Doses and Endpoints for Amicarbazone for Use in Human Health Risk 

Assessments.

Exposure/ 

Scenario

Point of 

Departure

Uncertainty/FQPA 

Safety Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Incidental Oral 

Short-Term

(1-30 days)

NOAEL= 

6.28

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Residential 

LOC for 

MOE = 100

90-Day Oral Toxicity in Dogs

LOAEL = 25 mg/kg/day based on 

increased thyroid vacuolization and 

decreased food consumption and glucose 

in females; increased platelets, phosphate, 

bile acids, absolute and relative liver 

weights, and lymphoid hyperplasia of the 

gall bladder in males; and decreased 

albumin and increased triglycerides, Ndemethylase and O-demethylase in both 

sexes.

Dermal (all 

durations)

No systemic toxicity was observed at the limit dose. Evidence of low dermal absorption was 

estimated by comparison of oral and dermal studies in the rat.
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Table 2. Summary of Toxicological Doses and Endpoints for Amicarbazone for Use in Human Health Risk 

Assessments.

Exposure/ 

Scenario

Point of 

Departure

Uncertainty/FQPA 

Safety Factors

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Inhalation 

Short- and 

IntermediateTerm (1-30 

days and 1-6 

months, 

respectively)

NOAEL=

6.28

mg/kg/day

(Inhalation

toxicity 

considered 

equivalent 

to oral 

toxicity)

UFA= 10x

UFH=10x

FQPA SF= 1x

Occupational/

Residential 

LOC for 

MOE = 100

90-Day Oral Toxicity in Dogs

LOAEL = 25 mg/kg/day based on 

increased thyroid vacuolization and 

decreased food consumption and glucose

in females; increased platelets, phosphate, 

bile acids, absolute and relative liver 

weights, and lymphoid hyperplasia of the 

gall bladder in males; and decreased 

albumin and increased triglycerides, Ndemethylase and O-demethylase in both 

sexes.

Cancer (oral, 

dermal, 

inhalation)

Classification: There was no treatment-related increase in tumor incidence when compared to 

control. Dosing was considered adequate. This chemical is not likely to be a carcinogen.

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. MOE = margin of 

exposure. LOC = level of concern. 

3.0 Proposed Use Patterns

Amicarbazone, 4-amino-4,5-dihydro-N-(1,1-dimethylethyl)-3-(1-methylethyl)-5-oxo-1H-1,2,4-

triazole-1-carboxamide, is a triazolinone compound proposed for the control of annual broadleaf 

weeds. Amicarbazone selectively inhibits acetolactase synthase, an enzyme involved in 

photosystem II of plants. Related compounds include carfentrazone, flucarbazone, 

propoxycarbazone, and sulfentrazone.

Arysta LifeSciences North America, LLC is currently seeking use of amicarbazone for control of 

broadleaf weeds in turf (i.e., lawns, sod farms, golf courses, recreational fields, etc), ornamentals, 

non-crop areas, Christmas tree farms and conifers in nurseries. Amicarbazone is formulated as a 

70% dry flowable powder. It is intended for pre-emergence and post-emergence applications. 

Broadcast applications are to be made with ground equipment only; spot treatments are to be 

made using backpacks and hand held equipment. The product is not to be applied by aerial 

equipment or through irrigation systems.

Amicarbazone is available for use by commercial and professional applicators. This herbicide 

works best when applied and subsequently moved into the soil by rainfall. The personal 

protective equipment (PPE) for the proposed label consists of baseline clothing (i.e., longsleeved shirt and long pants, shoes and socks) and use of chemical resistant gloves. The 

proposed uses are anticipated to result in short- and intermediate-term exposure durations. Table 

3 provides a summary of the proposed uses.
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Table 3. Proposed Products and Uses of Amicarbazone.

Product Trade 

Name

(EPA Reg. No.)

Crops Method of 

Application

Maximum 

Application 

Rates

†

Maximum

Seasonal 

Application

Rates

Maximum #

Applications

per Season

Use Directions and other 

Limitations‡

Amicarbazone 

DF Herbicide 

(DINAMIC

70 WDG

HERBICIDE)

70% ai

(EPA Reg. No. 

66330-46)

Turf, golf course, 

sod farms, parks and 

recreation areas, 

athletic fields, 

landscape plants and 

tree nurseries, and 

Christmas trees 

farms 

Directed;

Broadcast 

using ground 

equipment 

only.

Spot treatment 

using backpack 

and 

compression 

sprayers.

0.46 lb ai/A 

(single 

application)

(10.5 oz 

prod/A)

(0.023 lb 

ai/gal)

0.46 lbs ai/ 

A/yr

1 appl at the 

max appl. rate.

2-4 appls for turf 

grass at a lower 

rate.

12-hr REI

Application intervals from 

14-21 days, but may vary 

depending on application 

rate.

Do not apply within 4 

weeks of cutting or lifting 

sod.

Do not apply this product 

using aerial equipment or 

any irrigation system.

† Max Single Application Rate = (70% ai) (1 lbsolid/16 oz) (10.5 oz/A) = 0.46 lb ai/A (1 A/20gal) = 0.023 lb ai/gal.

‡ Minimum Spray Volume = 20 gal/A.

Note: The proposed label states that the maximum single application rate for turf is 10 oz 

prod/A. However, for purposes of this assessment HED used the maximum single application 

rate of 10.5 oz prod/A based on information provided by the registrant (MRID No. 48237522). 

4.0 Residential (Non-Occupational) Exposure

4.1 Residential Handler Exposure and Risk

The Agency uses the term “Handlers” to describe those individuals who are involved in the 

pesticide application process. Based on the proposed label (EPA Reg. No. 66330-46) and 

information provided by the registrant (MRID No. 48237522), this product is to be applied by

professional applicators. The proposed label includes occupational/commercial mixing/loading 

activities, PPE and REI requirements. However, since the proposed label does not identify this 

product as a restricted use pesticide, a residential handler exposure assessment was performed to 

be protective of potential homeowner exposure. 

The following exposure scenarios and unit exposures were used to assess residential handlers for 

broadcast and spot treatments:

 Mixing/Loading/Applying for Sprays with Backpack Sprayer;

 Mixing/Loading/Applying for Sprays Using Low-Pressure Handwand; and,

 Mixing/Loading/Applying for Sprays with Hand-Gun Sprayer (hose-end).

4.1.1 Data and Assumptions

Unit Exposures: No chemical specific unit exposure data were provided in support of this 

submission; therefore, HED used data from the PHED Surrogate Exposure Guide for Residential 

Handlers, Version 1.1, August 1998 and the Occupational Residential Exposure Task Force 

(ORETF) (MRID 449722-01).
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Acres/Amount Treated: Information regarding area treated for the various use scenarios was 

provided by the Science Advisory Council for Exposure Policy #12: Recommended Revisions to 

the Standard Operating Procedures (SOPs) for Residential Exposure Assessments. 

Exposure Duration: Based on information provided in the proposed labels, residential handler 

exposure is anticipated to be short-term in duration. 

Body Weight: The average adult body weight of 70 kilograms was used to assess handler 

exposure since the endpoints were not gender specific.

4.1.2 Residential Handler Exposure and Risk Estimates

A quantitative dermal assessment for residential handlers was not conducted since no systemic 

toxicity by the dermal route was seen at the limit dose in the dermal toxicity study. Handler 

inhalation exposure scenarios resulted in MOEs greater than 100 and therefore are not of 

concern. Handler exposure and risk estimates are summarized in Table 4. 

Table 4. Residential Handler Exposure Estimates for Amicarbazone.

Scenario Inhalation Unit 

Exposurea

(mg/lb ai)

Application Rate b Amount Treated cInhalation Dosed

(mg/kg/day)

Inhalation MOE e

Mix/Load/Apply

Backpack

Sprayer

(Ground 

Directed)

0.03 (Baseline)

(PHED)

0.023

lb ai/gal

5 Gal 0.0000493 130,000

Low Pressure 

Handwand 

1.063 (Baseline)

(PHED)

5 Gal 0.00175 3,600

Hose-end (for 

Handgun

Sprayer)

(Mix your own) 

0.017 (Baseline) 

(ORETF-OMA004)

0.023 lb ai/gal 5 Gal 0.000028 220,000

0.46

lb ai/A

0.5 A 0.000056 110,000

a. PHED Surrogate Exposure Guide for Residential Handlers, Version 1.1, August 1998. Occupational Residential 

Exposure Task Force (ORETF) Study Data (MRID 449722-01).

b. Application Rate = (70% ai) (1 lbsolid/16 oz) (10.5 oz/A) = 0.46 lb ai/A (1 A/20gal) = 0.023 lb ai/gal.

c. Policy 12: Recommended Revision to the SOPs for Residential Exposure Assessment.

d. Inhalation Dose (mg/kg/day) = Inhalation Unit Exposure (mg/lb ai) * Application Rate * Acres Treated or 

Amount Handled / Body Weight (70 kg).

e Inhalation MOE = NOAEL (6.28 mg/kg/day) / Inhalation Dose (mg/kg/day).
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4.2 Residential Postapplication Exposure

Amicarbazone residential postapplication scenarios include children (3 to 6 years) playing on 

treated turf, adults performing yard work on treated turf and adults playing golf on treated turf. 

As a result, a wide array of individuals of varying ages can potentially be exposed when they do 

activities in areas that have been treated.

The postapplication scenarios were assessed using the HED Draft Standard Operating 

Procedures (SOP’s) for Residential Exposure Assessments, 2000. Since no chemical-specific 

residue data were submitted for this action, postapplication exposures were assessed using 

default assumptions from the Residential Exposure SOPs. 

4.2.1 Inhalation Postapplication Exposure

Based on the Agency's current practices, a quantitative postapplication inhalation exposure 

assessment was not performed for amicarbazone at this time primarily because of the low acute 

inhalation toxicity (Toxicity Category IV) , the low vapor pressure (2.3 x 10-8 mm Hg) and the 

proposed application rate (0.46 lb ai/A). However, volatilization of pesticides may be a potential 

source of postapplication inhalation exposure to individuals nearby to pesticide applications. 

The Agency sought expert advice and input on issues related to volatilization of pesticides from 

its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in 

December 2009, and received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The Agency is in the 

process of evaluating the SAP report and may, as appropriate, develop policies and procedures to 

identify the need for and, subsequently, the way to incorporate post-application inhalation 

exposure into the Agency's risk assessments. If new policies or procedures are developed, the 

Agency may revisit the need for a quantitative pos-application inhalation exposure assessment 

for amicarbazone.

4.2.2 Dermal Postapplication Exposure

In assessing potential dermal postapplication exposure and risk estimates, HED assumes that 

pesticide residues are transferred to the skin of adults/children who enter treated yards for 

recreation or other activities such as yard work and golfing. However, a quantitative 

postapplication dermal exposure assessment was not performed for adults and children since no

dermal endpoints were selected. If dermal toxicological endpoints change in the future, HED 

may require a turf transferable residue (TTR) study to confirm that assessments are protective of 

all turf uses. 

4.2.3 Non-Dietary Ingestion (Hand-to-Mouth) Exposure

For the assessment of non-dietary ingestion (hand-to-mouth) exposure, HED assumes that 

pesticide residues are transferred to the skin of children playing on treated areas and are 

subsequently ingested as a result of hand-to-mouth transfer.
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Assumptions:

 On the day of application, it is assumed that 5% of the application rate is available on turf 

grass as transferable residue.

 Oral postapplication exposure was estimated using the standard assumption for the initial 

fraction of residues available and assuming a 10% daily dissipation rate. 

 The median surface area of both hands is 20 cm2for children.

 It is assumed that there is a one-to-one relationship between the dislodgeable residues on 

the turf and on the surface area of the skin after contact.

 The mean rate of hand-to-mouth activity is 20 times/hour for short-term exposure 

scenarios.

 The saliva extraction factor is 50%.

 The children (3-6 yrs) are assumed to weigh 15 kg.

 Duration of exposure for children is assumed to be 2 hours per day for turf.

Equations:

TTRt = AR x F x (1-D)tx CF2 x CF3 

TTR = Turf Transferable Residue;

AR = Application rate (lb ai/acre);

F = Fraction of ai available on turf (unitless) (0.05);

D = Fraction of residue that dissipates daily (unitless) (0.1);

t = Postapplication day on which exposure is being assessed;

CF2 = Weight unit conversion factor to convert the lbs ai in the application rate to ug for DFR

value (4.54 x 108ug/lb); and,

CF3 = Area unit conversion factor to convert the surface area units (acre) in the application rate 

to cm2for the DFR value (2.47 x 10-8acre/cm2).

 

PDR = TTR x SA x FQ x ET x SE x CF1 

BW

 

PDR = Potential dose rate (mg/day);

TTR = Turf transferable residue (ug/cm2turf);

SA = Surface area of the hands (20 cm2/event);

FQ = Frequency of hand-to-mouth activity (20 events/hr for short-term) ;

ET = Exposure time (hr/day);

CF1 = Weight unit conversion factor to convert ug units in the TTR value to mg for the daily

exposure (0.001 mg/ug for turf);

SE = Saliva Extraction Factor (50%); and,

BW = Body Weight (15 kg).

Hand-to-Mouth Exposure and Risk Estimate

Short-term hand-to-mouth (HTM) exposure resulted in an MOE greater than the level of concern 

(MOEs ≥ 100) and therefore poses no risk of concern. Table 5 provides a summary of the shortterm HTM exposure estimate.
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Table 5. Amicarbazone Children’s Short-term Non-Dietary Ingestion (Hand-to-Mouth) Exposure and Risk Estimate.

Product TTR 1 

(ug/cm2)

SA 

(cm2/event)

FQ SE ET 

(hr/day)

CF1 BW 

(kg)

HTM Dose 2

(mg/kg/day)

HTM 

MOE 3

Amicarbazone DF 

Herbicide (DINAMIC 

70 WDG HERBICIDE)

70% ai

(EPA Reg. No. 66330-46)

0.2576 20 20 0.5 2 0.001 15 0.00687 910

1. Turf Transferable Residues = (TTR) = 

AR (0.46 lb ai/A) x F (0.05) x (1-D)0x CF2 (4.54E8μg/lb) x CF3 (2.47E-8acre /cm2) = 0.2576 ug/cm2.

2. HTM Dose = [TTRt x SA x FQ x ET x SE x CF1]/BW.

3. HTM MOE = NOAEL (6.28 mg/kg/day)/HTM Dose (mg/kg/day).

4.2.4 Non-Dietary Ingestion (Object to Mouth Ingestion of Treated Turf) Exposure

This scenario estimates exposure to children (3-6 yrs) resulting from incidental ingestion of 

pesticide and/or residential turf grass that has been treated with pesticides. It assumes that 

pesticide from a treated object or turf is ingested by children who play on treated areas. 

Assumptions:

 On the day of application it is assumed that 20% of the application rate is available to be 

ingested.

 Oral postapplication exposure was estimated using the standard assumption for the initial 

fraction of residues available and assuming a 10% daily dissipation rate. 

 Assumed ingestion rate for grass for children (3 years old) is 25 cm2/day.

 Children are assumed to weigh 15 kg.

Equations:

GRt = AR x F x (1-D)tx CF2 x CF3

GRt = grass residue on day t (ug/cm2);

AR = application rate (lb ai/A);

F = fraction of ai available on the grass (unitless) (0.2);

D = fraction of residue that dissipates daily (unitless) (0.1);

t = postapplication day on which exposure is being assessed;

CF2 = weight unit conversion factor to convert the lbs ai in the application rate to μg for grass

residue value (4.54 x 108μg/lb); and,

CF3 = area unit conversion factor to convert surface area units (A) in the application rate to cm2

for grass residue value (2.47 x 10-8 A/cm2).

PDD = GR t x IgR x CF1

PDD = potential daily dose (mg/kg/day);

GRt = grass residue (ug/cm2);

IgR = ingestion rate of grass (cm2/day); and,
Page 13 of 20

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

units of mg/day (1.0 x 10-3 mg/μg).

Object-To-Mouth Exposure and Risk Estimate

The object-to-mouth (OTM) scenario resulted in an MOE greater than the level of concern 

(MOEs ≥ 100) and therefore poses no risk of concern. Table 6 provides a summary of the OTM 

exposure and risk estimate.

Table 6. Amicarbazone Children’s Non-Dietary Ingestion (Object–to-Mouth) Exposure and 

Risk Estimate.

Product GR 1 

(ug/cm2)

CF1

(mg/μg)

IgR 

(cm2/day) 

BW 

(kg)

OTM Dose 2 

(mg/kg/day)

OTM 

MOE 3

Amicarbazone DF Herbicide 

(DINAMIC 70 WDG 

HERBICIDE)

70% ai

(EPA Reg. No. 66330-46)

1.03 0.001 25 15 0.0017 3,700

1. GR (grass residue) = Application Rate x F x (1-D)0x CF2 x CF3.

2. OTM Dose = [GR 0 x IgR x CF1]/BW.

3. OTM MOE = NOAEL (6.28 mg/kg/day)/OTM Dose (mg/kg/day).

4.2.5 Non-Dietary Ingestion Incidental Ingestion of Soil 

This scenario assumes children who play on treated areas ingest pesticide residues in soil as a 

result of normal mouthing activities. 

Assumptions: 

 On the day of application, it is assumed that 100% of the application rate is located 

within the soil’s uppermost 1 cm.

 Postapplication must be assessed on the same day the pesticide is applied.

 Assumed soil ingestion rate for children is 100 mg/day.

 Children are assumed to weigh 15 kg.

Equations:

SR0 = AR x F x (1-D)tx CF2 x CF3 x CF4

SR0 = soil residue on day 0 (ug/g);

AR = application rate (lb ai/A);

F = fraction of ai available in uppermost cm of soil (1 cm);

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

t = postapplication day on which exposure is being assessed (day 0);

CF2 = weight unit conversion factor to convert the lbs ai in the application rate for soil residue 

value (4.54 x 108μg/lb);

CF3 = area unit conversion factor to convert surface area units (A) in the application rate to cm2 

for soil residue value (2.47 x 10-8 A/cm2); and,

CF4 = volume to weight unit conversion factor to convert the volume units (cm3) to weight units 
Page 14 of 20

for the SR value (0.67 cm3/g soil).

PDD = SR0 x IgR x CF1

PDD = potential daily dose on day 0;

SR0 = soil residue on day 0 (ug/g);

IgR = ingestion rate of soil (mg/day); and,

CF1 = weight unit conversion factor to convert the μg of residues on the soil to mg to provide 

units of mg/day (1.0 x 10-6g/μg).

Soil Ingestion Exposure and Risk Estimate

The soil-ingestion scenario resulted in a MOE much greater than the level of concern (MOEs ≥ 

100) and therefore poses no risk of concern. This assessment should be considered conservative 

in that it assumed no dissipation of soil residues would occur over the exposure period. Table 7

provides a summary of the soil ingestion exposure and risk estimate.

Table 7. Amicarbazone Children’s Soil Ingestion Exposure and Risk Estimate.

Product SR 1 

(ug/g)

CF1

(g/μg)

IgR 

(mg/day) 

BW 

(kg)

Dose 2 

(mg/kg/day)

MOE 3

Amicarbazone DF Herbicide 

(DINAMIC 70 WDG 

HERBICIDE)

70% ai

(EPA Reg. No. 66330-46)

3.45 0.000001 100 15 0.000023 270,000

1. SR0(soil residue) = Application Rate (lb ai/A) x F(1) x (1-D)0x 0.67 x (4.54x108μg/lb)x (2.47 x 10-8 A/cm2).

2. Soil Ingestion Dose (mg/kg/day) = SR0 (μg/g) x IgR (mg/day) x CF1 (g/μg)/BW (kg).

3. Soil Ingestion MOE = NOAEL (6.28 mg/kg/day)/Soil Ingestion Dose (mg/kg/day).

4.3 Summary of Residential Risk Estimates

HED combines risk values resulting from separate exposure scenarios when it is likely they can 

occur simultaneously based on the use pattern and the behavior associated with the exposed 

population. In evaluating combined residential uses of amicarbazone, HED reviewed all 

residential sources of exposure which consisted of: 1) adult inhalation handler (lawns only) 

exposure, and 2) child postapplication oral exposure. 

Since a dermal endpoint was not selected for amicarbazone, the only relevant route of exposure 

for adults is through the inhalation route, and therefore, a combined residential exposure 

assessment is not applicable. 

The children’s oral exposure estimate for the purpose of conducting an aggregate risk assessment 

is based on postapplication hand-to-mouth exposures only. To include exposure from object-tomouth and soil ingestion in addition to hand-to-mouth could result in a very conservative 

estimate of exposure since the assumptions for each of the individual oral exposure calculations 

are high end.
Page 15 of 20

The hand-to-mouth residential postapplication scenario also represents the worst case of oral 

exposure (i.e., to include exposure from object-to-mouth and soil ingestion in addition to handto-mouth could result in a very conservative estimation of exposure as it would overestimate the 

potential of oral exposure). Table 8 identifies the residential scenarios and MOEs for adults and 

children for use in performing an aggregate exposure assessment as part of the amicarbazone

human health risk assessment. There are no risks of concern.

Table 8. Amicarbazone Summary of Residential Exposure and Risk Estimates.

Product Use Site Handler 

Inhalation

MOE 1

Postapplication 

Dermal MOE 

Hand-to-Mouth 

MOE 2

Combined 

MOE 3

Adult 

Amicarbazone DF 

Herbicide (DINAMIC 

70 WDG HERBICIDE

(EPA Reg. No. 66330-46)

Lawns (turf)

3,600 NA NA NA

Child

Amicarbazone DF 

Herbicide (DINAMIC 

70 WDG HERBICIDE)

(EPA Reg. No. 66330-46)

Lawns (turf)

NA NA 910 NA

1. See Table 4: Residential Handler Exposure and Risk (Low Pressure Handwand).

2. See Table 5. Hand-To-Mouth Exposure and Risk.

3. Child MOE = NOAEL (6.28 mg/kg/day)/HTM Dose (0.00687 mg/kg/day).

4.4 Spray Drift

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

This is particularly the case with aerial application, but, to a lesser extent, could also be a 

potential source of exposure from the ground application method employed for amicarbazone. 

The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State 

Lead Agencies for pesticide regulation and other parties to develop the best spray drift 

management practices (see the Agency’s Spray Drift website for more information at 

http://www.epa.gov/opp00001/factsheets/spraydrift.htm). On a chemical by chemical basis, the 

Agency is now requiring interim mitigation measures for aerial applications that must be placed 

on product labels/labeling. The Agency has completed its evaluation of the new database 

submitted by the Spray Drift Task Force, a membership of U.S. pesticide registrants, and is 

developing a policy on how to appropriately apply the data and the AgDRIFT computer model to 

its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic methods. 

After the policy is in place, the Agency may impose further refinements in spray drift 

management practices to reduce off-target drift with specific products with significant risks 

associated with drift.

It is noted that the 0.46 lb ai/acre application rate for turf was modeled to estimate 

postapplication residential exposure of children. As this rate is the same as the maximum 

agricultural single application rates (0.46 lb ai/A), this scenario is protective of any exposure of 

farm children via spray drift from agricultural applications of amicarbazone.
Page 16 of 20

5.0 Occupational Exposure

Amicarbazone DF Herbicide (Alternate Brand Name: DINAMIC 70 WDG Herbicide), is a dry

flowable (water-dispersible granular) formulation for the control of weeds in turfgrass, including 

golf courses (i.e., fairways, roughs, tees and approaches), seed production, sod production, and 

residential and commercial sites (i.e., homes, schools, playgrounds, parks, recreational areas, 

sports fields and common areas) as well as in tree sites (i.e., tree nurseries and Christmas tree 

farms). This product will be applied as a spray after mixing with water or a liquid fertilizer. 

Based on information provided by the registrant, this product is intended to be applied only by 

professional applicators (MRID No. 48237522). Therefore, the potential for occupational 

handler and postapplication exposure does exist.

5.1 Occupational Handlers

Based upon the proposed use pattern, HED expects the most highly exposed occupational 

pesticide handler scenarios to be:

1) mixing/loading dry flowable for ground applications;

2) applying sprays via open cab groundboom equipment; 

3) mixing/loading/applying liquids with manually pressurized (low-pressure) handwand;

and,

4) mixing/loading/applying liquids with a backpack sprayer.

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

provided on proposed labels. Long-term exposures are not expected; therefore, a long-term 

assessment was not conducted. 

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 the 

Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1), the Agricultural Handler 

Exposure Task Force (AHETF) database, and the Outdoor Residential Exposure Task Force 

(ORETF) database. Some of these data are proprietary (e.g., AHETF data, MRID No. 

44339801), 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 Table” (http://www.epa.gov/opp00001/science/handler-exposure-table.pdf), which, 

along with additional information on HED policy on use of surrogate data, including descriptions 

of the various sources, can be found at http://www.epa.gov/pesticides/science/handler-exposuredata.html.

For pesticide handlers, it is HED standard practice to present estimates of dermal exposure for 

“baseline”, that is, for workers wearing a single layer of work clothing consisting of a long 

sleeved shirt, long pants, shoes plus socks and no protective gloves, as well as for “baseline” and

the use of protective gloves or other Personal Protective Equipment (PPE) might be necessary to 
Page 17 of 20

achieve a MOE greater than the LOC. The proposed product label involved in this assessment 

directs applicators and other handlers to wear long sleeved shirt and long pants, shoes plus socks, 

and chemical-resistant gloves. 

Body Weight:

The standard body weight for the general population (70 kg) was used for all exposure scenarios 

covered in this risk assessment.

 

Dermal Absorption:

Although a dermal absorption rate of 5% was calculated for amicarbazone, HED has concluded 

that a dermal risk assessment is not needed.

Exposure Frequency:

No data on the number of exposure days per year was provided. For this risk assessment, it was 

assumed that handlers would be exposed for less than 6 months per year (i.e. short-/intermediateterm durations). 

Equations:

Daily handler exposures are estimated for each applicable handler task with the application rate, 

the area treated in a day, and the applicable dermal and/or inhalation unit exposure using the 

following formula:

Daily Exposure (mg ai/day) = 

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

Where: 

Daily Exposure = Amount (mg or μg ai/day) inhaled that is available for inhalation 

absorption or amount absorbed that is available for dermal absorption;

Unit Exposure = Unit exposure value (mg or μg ai/lb ai) derived from OPHED;

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

acres, square feet, or gallons. Maximum values are generally used (lb 

ai/A, lb ai/sq ft, lb ai/gal); 

Daily Area Treated = Normalized application area based on a logical unit treatment such as 

acres (A/day), square feet (sq ft/day), gallons per day (gal/day); and,

The daily dose is calculated by normalizing the daily exposure by body weight and adjusting, if 

necessary, with an appropriate dermal and/or inhalation absorption factor using the following 

formula:

Average Daily Dose (mg/kg/day) = 

[Daily Exposure (mg ai/day) x Absorption Factor] / Body Weight (kg))

Where:
Page 18 of 20

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

given scenario (mg pesticide active ingredient/kg body 

weight/day);

Daily Exposure = Amount (mg ai/day) inhaled/absorbed that is available for 

inhalation/dermal absorption;

Absorption Factor = A measure of the amount of chemical that crosses a biological 

boundary such as the lungs/skin; and

Body Weight = Body weight determined to represent the population of interest 

in a risk assessment (70 kg for amicarbazone).

Risks for each applicable handler scenario are calculated using a MOE, which is a ratio of the 

NOAEL or LOAEL to the daily dose. In the case of amicarbazone, a NOAEL was used in the 

calculation. All MOE values were calculated using the formula below:

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

Occupational Handler Exposure and Risk Estimates

Table 9 presents the estimated short- and intermediate-term inhalation risks for workers. All 

occupational handler scenarios resulted in MOEs greater than the level of concern at the baseline 

PPE level of protection (i.e. single layer clothing and no respirator). The MOEs shown in the

table are all significantly higher than HED’s level of concern of an MOE of 100, with the lowest 

MOE of 1,300 identified for handlers conducting mixing/loading activities for application to sod 

farms. 

Based on communication with the registrant, the proposed label will prohibit the use of a 

mechanically pressurized handgun for application to Christmas trees. 
Page 19 of 20

Table 9. Occupational Handler Exposures and Risks Estimates for Amicarbazone.

Exposure 

Scenario and 

Product

Crops

Application 

Ratea

Area Treated or 

Amount Treated

Inhalation Unit 

Exposure b

(mg/lb)

Inhalation Dose c

(mg/kg/day)

Inhalation MOE d

Mixer/Loader

Ground –

Dry Flowable

Golf courses 0.46

lb ai/A

40 A

0.00896 (Baseline)

(AHETF)

0.00235 2,700

Sod farms (turf), 

Christmas trees

80 A 0.00471 1,300

Applicator

Open Cab 

Groundboom

Golf courses 

0.46

lb ai/A

40 A 0.00034 (Baseline)

(AHETF)

0.0000894 70,000

Sod farms (turf), 

Christmas trees

80 A 0.000178 35,000

Mixer/Loader/Applicator

Backpack Sprayer 

Christmas trees

(Ground-Directed)

0.023 lb ai/gal 5 gals 0.00258 (Baseline)

(MRID 44339801) 0.0000042 1,500,000 Turf, golf course, 

sod farms, parks, 

recreation and 

athletic fields 

Manuallypressurized 

Handwand

Turf, Christmas trees 0.023 lb ai/gal 5 gals 0.03 (Baseline)

(PHED) 0.000049 130,000

Mechanicallypressurized 

Handgun Sprayer

(WDG)

Turf, golf courses

(Broadcast)

0.46

lb ai/A 5 A0.042 (Baseline)

(ORETF)

0.00138 4,500

a. Application Rate = (70% ai) (1 lbsolid/16 oz) (10.5 oz/A) = 0.46 lb ai/A (1 A/20gal) = 0.023 lb ai/gal.

b. Occupational Pesticide Handler Unit Exposure Surrogate Reference Table (September 26, 2011).

c. Inhalation Dose (mg/kg/day) = Inhalation Unit Exposure (mg/lb ai) * Application Rate * Acres Treated or Amount Handled / Body Weight (70 kg).

d. Inhalation MOE = NOAEL (6.28 mg/kg/day) / Inhalation Dose (mg/kg/day).
Page 20 of 20

5.2 Occupational/Commercial Postapplication Exposure 

5.2.1 Postapplication Inhalation Exposure

Based on the Agency's current practices, a quantitative postapplication inhalation exposure 

assessment was not performed for amicarbazone at this time primarily because it has a low vapor 

pressure (2.3 x 10-8 mm Hg), it is applied at a maximum single application rate of 0.46 lb ai/A

and it is not projected to be applied via typically high inhalation exposure application equipment 

(e.g., airblast and aerial equipment). However, volatilization of pesticides may be a potential 

source of postapplication inhalation exposure to individuals nearby to pesticide applications. 

The Agency sought expert advice and input on issues related to volatilization of pesticides from 

its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel (SAP) in

December 2009. The Agency received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The Agency is in the 

process of evaluating the SAP report and may, as appropriate, develop policies and procedures to 

identify the need for and, subsequently, the way to incorporate postapplication inhalation 

exposure into the Agency's risk assessments. If new policies or procedures are put into place, the 

Agency may revisit the need for a quantitative postapplication inhalation exposure assessment 

for amicarbazone.

Although a quantitative occupational postapplication inhalation exposure assessment was not 

performed, an inhalation exposure assessment was performed for occupational/commercial 

handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in 

higher exposure than postapplication exposure. Therefore, it is expected that these handler 

inhalation exposure estimates would be protective of occupational postapplication inhalation 

exposure scenarios.

5.2.2 Postapplication Dermal Exposure

Postapplication exposure assessments were not performed because no dermal endpoints were 

selected.

Restricted Entry Interval

The restricted entry interval (REI) listed on proposed labels is based on the acute toxicity of the 

technical material. Amicarbazone exhibits low acute toxicity and is classified as Toxicity

Category III for eye irritation and Category IV for acute dermal and dermal irritation. It is not a 

dermal sensitizer. Acute toxicity Category III and IV chemicals require a 12-hour REI. 

Therefore, the 12-hour REI which appears on the proposed labels is considered appropriate.