UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHING TON D.C., 20460 

MEMORANDUM 

SUBJECT: 

TO: 

FROM: 

THROUGH: 

PEER REVIEW: 

OFFICE OF 

CHEMICAL SAFETY ANO 

POLLUTION PREVENTION 

DP Barcode: D426603 

PC Code: 114004 

Date: September 10, 2015 

Amicarbazone Problem Formulation for Registration Review 

Maria Piansay, Chemical Review Manager 

Linda Arrington, Branch Chief 

Risk Management and Implementation Branch 5 

Pesticide Re-evaluation Division (7508P) .. /. 

Stephen Carey, Biologist ~ ~ 9'/! tJ/ I .f C/J. / 

William P. Eckel, Senior s~1c'~s~r - c/j / //', 0 P\ ,,,ft>-

Environmental Risk Branch 6 /(/ll~U · 

Environmental Fate and Effects Division (7507P) b, Ld r l - J l1 --) V' , t) 

Mark Corbin, Branch Chie~~\ 

Monica Wait, RAPL ~ vJo:J_, q / v 

Environmental Risk Branch 6 \ / \5 

Environmental Fate and Effects Division (7507P) 

Amy Blankinship, Senior Biologist 

Ibrahim Abdel-Saheb, Ph.D., Environmental Scientist 

Environmental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

The Environmental Fate and Effects Division (EFED) has completed the preliminary problem 

formu lation for the ecological risk and drinking water exposure assessments to be conducted as 

part of the registration review of the herbicide amicarbazone (PC Code 114004). This document 

is intended to provide an overview of what is currently known regarding the environmental fate 

and ecological effects associated with amicarbazone and its degradation products, and outlines 

uncertainties regarding attributes of the parent compound and its transformation products. It 

describes the preliminary ecological risk hypothesis and the processes that will be used during 

the completion of the preliminary ecological risk assessment in support of registration review. 
2 

As noted later in this document, additional data will be needed for the environmental fate and 

transport and ecological effects of amicarbazone to complete the risk assessment and registration 

review process. For the environmental fate and transport of amicarbazone, the following data are 

needed: 

• GDLN 835.4200 Anaerobic soil metabolism 

• GDLN 835.4300 Aerobic aquatic metabolism 

• GDLN 835.4400 Anaerobic aquatic metabolism 

With regard to the ecological effects database, additional studies EFED recommends be 

requested include passerine acute oral toxicity (GDLN 850.2100) and honey bee toxicity studies. 

A definitive NOAEC has not been established for chronic exposure to estuarine/marine 

invertebrates, which normally results in a presumption of risk for estuarine/marine invertebrates 

until available data show differently; however, in the absence of such data, EFED is not 

requiring a mysid chronic toxicity study to establish a definitive NOAEC because the lowest test 

concentration of 2400 μg a.i./L in the study needs to be 320x more toxic than to Daphnia to 

result in a chronic LOC exceedance when using the highest 21-day EEC of 7.5 μg a.i./L (EEC 

used in this calculation was obtained from the August 30, 2010 risk assessment for new use on 

turf grasses; D384516), which is unlikely. 

No data for the alkaline metabolite, decarboxamide, are available; however, because current 

labels bear language prohibiting application to coarse-textured soils (sand, loamy sand and sandy 

loam soils), or on soils with pH >7.4 (such as calcareous soils), data on the effect of the alkaline 

metabolite to aquatic organisms is not needed at this time. 

• Amicarbazone may cause exposure of pollinators visiting off-site plants that are 

contaminated by spray drift. Acceptable toxicity data to honey bee adults and larvae have 

not been submitted for amicarbazone and are now needed under EPA’s recent policy on 

pollinator protection1

. Thus, the following six Tier I, II and III honey bee studies, yet to 

be submitted for amicarbazone, are needed: 

o Honeybee larval acute oral toxicity study (following OECD 237) 

o Honeybee adult 10-day chronic oral (special study) 

o Honeybee larval repeated dose study (special study renamed as honeybee larval 

chronic oral toxicity study) 

o Field testing for pollinators (OCSPP 850.3040, Tier III) 

o Field trial of residues in pollen and nectar (special study, Tier II) 

o Semi-field testing for pollinators (special study, Tier II). 

• In addition, GDLN 850.2100 acute avian acute oral toxicity data (passerine species), per 

the 40 CFR Part 158 data requirements, are needed. 

 

1

 (Guidance for Assessing Pesticide Risks to Bees, 06.23.2014; signed by Donald Brady, Director, EFED; 

http://www2.epa.gov/sites/production/files/2014-

06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf) 
3 

INTRODUCTION 

Amicarbazone is a selective herbicide used to control annual broadleaf weeds in field and silage 

corn at several stages of crop development, conifers, and turf grasses. Amicarbazone belongs to 

the triazolinone class of compounds and is a photosystem II (PS II) inhibitor with burndown 

activity. Current label language indicates that this herbicide is not to be used on coarse-textured 

soils (sand, loamy sand and sandy loam soils), or on soils with pH >7.4, such as calcareous soils. 

The chemical structure of amicarbazone and several chemical identifiers are provided in Table 1. 

Table 1. Amicarbazone Chemical Identifiers

Chemical Name 4-Amino-4,5-dihydro-N-(1,1-dimethylethyl)-3-(1-

methylethyl)-5-oxo-1H-1,2,4-triazole-1-carboxamide

Chemical Structure 

Chemical Abstracts Service 

(CAS) Registry Number 129909-90-6 

Smiles Code NN(C(C(C)C)=NN1C(NC(C)(C)C)=O)C1=O 

Empirical Formula C10H19N5O2 

The use information for amicarbazone is provided in Table 2. There are currently three active 

end-use product registrations for amicarbazone. 

Table 2. Summary of Current Uses of Amicarbazone 

Parameter Registration # 66330-46 Registration # 

66330-415 

Registration # 

66330-416 

Restricted use? No 

Advisories Ground & surface water 

Sites Field corn, corn for silage Turf (golf course

tees, fairways, 

roughs; sod; 

residential; parks; 

etc.) 

Turf (golf course 

tees, greens, 

fairways, roughs; 

sod; residential; 

parks; etc.) 

Turf (golf course, seed & sod 

production, residential, parks 

etc.) 

Conifers (nursery and field plantings) 
4 

Table 2. Summary of Current Uses of Amicarbazone 

Parameter Registration # 66330-46 Registration # 

66330-415 

Registration # 

66330-416 

Target weeds Broadleaf including ALS 

resistant weeds; won’t control 

triazine resistant weeds; grasses 

Broadleaf; grasses 

Formulation type Water dispersible granule (70% 

a.i.) 

Suspension 

concentrate (4 lb 

a.i./gal) 

Suspension 

concentrate (2 lb 

a.i./gal) 

Application 

method 

No aerial, no chemigation 

Corn: broadcast 

surface/incorporated 

Turf: broadcast, spot treatment 

Conifer: over-the-top or 

directed spray under canopy 

No aerial, no chemigation 

Turf: broadcast, spot treatment 

Conifer: over-the-top or directed 

spray under canopy 

Application 

equipment 

Corn: broadcast boom 

Turf broadcast: sprayer (type 

not specified) 

Turf spot: backpack or 

compression sprayer 

Conifer: sprayer (type not 

specified); do not use 

mechanically pressurized 

handgun for Christmas trees 

Turf broadcast: spray boom or spraywand/gun 

Turf spot: backpack or compression 

sprayer 

Conifer: sprayer (type not specified); 

do not use mechanically pressurized 

handgun for Christmas trees 

Application timing Corn: IA, MN, ND, SD, WI, & 

northern NE, IL, & OH: from 

Oct. 15 until ground freezes 

(can follow w/spring 

application); KS, OK, TX; from 

November to w/in 30d of spring 

planting (can follow w/spring 

application); Eastern corn belt: 

spring 

Turf: spring only 

Conifer: unspecified 

Turf: weed post-emergence to 

actively growing weeds 

Conifer: when weeds are actively 

growing 

Max # apps/year Corn: 1, but if spring 

application follows fall 

application, total for both must 

not exceed 0.45 lb a.i./A 

Turf: varies w/rate (e.g., up to 

4); 

Conifer: 2 

Turf: varies with rate (up to 4) 

Conifer: 2 

Application rates in lb a.i./A 

Max single Corn: 0.45 

Turf broadcast: 0.44 

Turf spot: unspecified 

Turf broadcast: 0.45 

Turf spot: 0.13 

Conifer: 0.45 
5 

Table 2. Summary of Current Uses of Amicarbazone 

Parameter Registration # 66330-46 Registration # 

66330-415 

Registration # 

66330-416 

Conifer: 0.44 

Max annual Corn: 0.45 

Turf & Conifer: 0.45 

Turf & Conifer: 0.45 

Minimum 

retreatment 

interval 

Corn: (1 app only) 

Turf broadcast: 7d 

Turf spot: unspecified 

Conifer: unspecified 

Turf broadcast: 7d 

Turf spot: unspecified 

Conifer: unspecified 

PHI None specified Do not apply less than 4 weeks 

before cutting or lifting sod. 

Replant interval 

for rotational crop 

Corn: 0d; Turf: 12 months Turf: 12 months 

REI 12h 

PPE Long sleeved shirt, long pants, chemical resistant gloves, shoes + socks 

Comments Corn: conventional, 

conservation, & no-till; Turf: 

don’t use if annual bluegrass is 

desired turf; don’t use on turf 

less than 6 months old; don’t 

use on coarse textured soils 

(sand, loamy sand and sandy 

loam soils), or on soils with pH 

>7.4, such as calcareous soils; 

water-in 

Turf: don’t use if annual bluegrass is 

desired turf; don’t use on turf less 

than 6 months old; don’t use on 

coarse textured soils (sand, loamy 

sand and sandy loam soils), or on 

soils with pH >7.4, such as 

calcareous soils; water-in 

Previous Ecological Assessments 

Amicarbazone was assessed as a new chemical in 2005 for use on field and silage corn 

(D288631) and in 2010 for additional uses on turf grasses and conifers (D384516). EFED 

reviewed these previous assessments for amicarbazone in association with the current toxicity, 

exposure, and use information to determine if sufficient data are available and if further updates 

are needed to support registration review. In the previous assessments, risks were assessed using 

the parent compound only due to available metabolite data indicating the metabolites are less 

toxic than the parent. 

A summary of previous risk concerns identified is provided in Table 3. 
6 

Table 3. Summary of Previous Risk Concerns Identified for Amicarbazone 

Taxa with 

Acute LOC 

Exceeded 

Taxa with 

Chronic LOC 

Exceeded 

Taxa with no 

LOC Exceedance BCF2 Persistence Degradates of Concern 

Terrestrial and 

Aquatic 

Nonvascular 

Plants 

Birds and 

Mammals 

Aquatic 

Organisms, 

Aquatic Vascular 

Plants, and 

Terrestrial 

Invertebrates1

No Yes No 

1 Based on acute contact and oral toxicity with adult bees; were not assessed quantitatively. 

2

 Bioconcentration Factor

Previous Drinking Water Exposure Assessments 

The most recent Drinking Water Assessment for amicarbazone was completed in September 

2011 (DP 384659). The surface water and groundwater estimates were calculated using 

PRZM/EXAMS and SCI-GROW, respectively. Estimates for surface water and groundwater use 

the total toxic residues of amicarbazone including the desamino and N-methyl desamino 

degradates as well as unextracted residues. The groundwater Estimated Drinking Water 

Concentrations (EDWCs) were found to be higher than the surface water EDWCs. 

Clean Water Act Programs 

Amicarbazone is not identified as a cause of impairment for any water bodies listed as impaired 

under section 303(d) of the Clean Water Act. Total Maximum Daily Load (TMDL) criteria have 

not been developed for amicarbazone. The link to TMDL reports is provided - 

(http://iaspub.epa.gov/tmdl_waters10/attains_impaired_waters.tmdls?p_pollutant_group_id=885) 

Aquatic benchmarks have not been established for amicarbazone 

(http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm). Any data submitted 

or otherwise located as part of the registration review process may be used to revise or establish 

new aquatic life benchmarks, if applicable. 

ENVIRONMENTAL FATE AND TRANSPORT 

Physical and Chemical Properties of Amicarbazone 

Selected physicochemical properties of amicarbazone are shown in Table 4. Based on these 

properties alone, volatility is not expected to be a major dissipation pathway for amicarbazone, 

and amicarbazone is not expected to bioaccumulate. 
7 

Table 4. Selected Physical/Chemical Parameters of Amicarbazone 

Chemical name Property Data Source 

(MRID) 

Molecular weight 241 451215-01 

Aqueous Solubility 4,600 mg/L 451215-01 

Melting Point 137.5°C 451215-01 

Boiling Point Decomposes above 180°C 451215-01 

Vapor Pressure 9.8x10-9 mmHg at 20°C 

2.2x10-8 mmHg at 25°C 451215-01 

Henry’s Law Constant 

1.5x10-12 atm m3 mol-1 

(calculated from vapor pressure and 

solubility values) 

451512-01 

Octanol-water partition coefficient 

(Kow) 

14 unbuffered 

15 at pH 4 

17 at pH 7 and 9 

451512-01 

Environmental Fate and Transport of Amicarbazone

Table 5 below summarizes the environmental fate properties of amicarbazone, while Appendix 

A provides the chemical structure of amicarbazone and its major degradation products. Due to 

its persistence and mobility, amicarbazone applications may lead to surface water contamination 

through spray drift, runoff, and sediment erosion, and groundwater contamination through 

leaching. 

Amicarbazone is moderately persistent in the environment as it eventually transforms by biotic 

mechanisms (t1⁄2= 87 days; aerobic soil metabolism). Under acidic and neutral environments, 

amicarbazone is stable to hydrolysis, but it transforms slowly under alkaline conditions. 

Photolysis also occurs slowly for amicarbazone in water and on soil with half-lives on the order 

of about two months, estimated for outdoor environmental conditions. The primary 

transformation products of amicarbazone are Desamino: N-(1,1-dimethylethyl)-4,5-dihydro-3-

(1-methylethyl)-5- oxo-1H-1,2,4-triazole-1-carboxamide; N-methyl Desamino: N-(1,1-

dimethylethyl)-4,5-dihydro-4-methyl-3-(1-methylethyl)-5-oxo-1H-1,2,4-triazole-carboxamide; 

and Decarboxamide: 4-amino-2,4-dihydro-5-(1-methylethyl)-3H-1,2,4-triazol-3-one. 

Amicarbazone has a low vapor pressure and Henry’s Law constant; therefore, volatilization from 

water and soil surfaces is not expected to be an important environmental fate process. The 

moderate persistence and high mobility of amicarbazone in soil make leaching of this compound 

to lower soil horizons and groundwater possible. Likewise, leaching and possible groundwater 

contamination with amicarbazone’s major three metabolites are possible due to their apparent 

long persistence and high mobility. 

All three amicarbazone end-use product labels include a use restriction that amicarbazone is not 

to be applied on soils with pH values higher than 7.4. Therefore, the fate of the chemical under 

neutral and acidic conditions only will be considered in the risk assessment. In such 

environments, two major amicarbazone transformation products (Desamino and N-methyl 
8 

Desamino) are expected to be formed. In metabolism studies, these metabolites increase in 

concentration to the end of study. Given the moderate persistence/high mobility and solubility of 

the parent compound and the apparent high persistence/high mobility of the two transformation 

products, both amicarbazone and its first two transformation products are expected to dissipate 

slowly and at the same time be vulnerable to leaching/run-off. Hydrolysis studies on the 

desamino and N-methyl desamino metabolites indicate stability at environmentally relevant 

temperatures and pH (MRIDs 48073601 and 48237506). If amicarbazone is transported into 

alkaline groundwater, surface water bodies, and/or soils, the third transformation product 

(Decarboxamide) may be formed; it is the only major metabolite identified in the base-catalyzed 

hydrolytic transformation of amicarbazone. 

Terrestrial field dissipation studies yielded half-lives (25 – 30 days) within the range obtained 

from laboratory aerobic metabolism studies (5 – 158 days). The desamino degradate was 

detected as a major degradate, indicating that microbial metabolism was likely a dissipation 

mechanism. 

Parent amicarbazone only will be considered in the risk assessment due to: 1) a freshwater green 

algae study indicating the desamino metabolite is less toxic than parent; 2) four avian 

reproduction studies indicating the metabolites, desamino and N-methyl, are less toxic than the 

parent; and 3) seedling emergence and vegetative vigor studies indicating the metabolites, 

desamino and N-methyl, are less toxic than the parent. 

Table 5. Amicarbazone (Parent) Environmental Fate Summary 

Parameter Value Source 

(MRID) Study Status

Hydrolysis half-life1 

Stable pH 5 & 7 

66.6 days pH 9 @ 25 °C 

451217-30 Acceptable 

Aqueous photolysis half-life1 

66.8 days 

Latitude: Phoenix, AZ 

@ 25 °C 

45121803 Acceptable 

Soil photolysis half-life1 

58.9 days 

Latitude: Phoenix, AZ 

@ 21 °C 

45121714 Supplemental

Aerobic soil metabolism half-life1 

At 20 °C 

Clay Loam Soil - 76.4 days 

Sandy Loam Soil - 5.1 days 

Loamy Sand Soil - 42.1 days 

Loam Soil - 26.2 days 

Clay Loam Soil – 158 days 

48237507

45121731

Supplemental

Supplemental

Anaerobic soil metabolism half-life No Data 

Aerobic aquatic metabolism half-life No Data 

Anaerobic aquatic metabolism halflife1 (total system) Stable @ 21 °C 45121724 Supplemental

Adsorption - Koc 35.6 (loam soil) 45121717 Acceptable 
9 

Table 5. Amicarbazone (Parent) Environmental Fate Summary 

Parameter Value Source 

(MRID) Study Status

Adsorption– Kfoc

24.2 (Clay Brazil) 

45121719 Supplemental

16.7 (Sandy clay Brazil) 

19.0 (Sandy clay Brazil) 

Desorption - Kfoc

17.2 (Clay Brazil) 

13.9 (Sandy clay Brazil) 

16.4 (Sandy clay Brazil) 

Adsorption– Kfoc

35.9 (silt loam, NE) 

45121732 Supplemental

32.0 (silt loam, LA) 

37.0 (silt loam, NE) 

22.9 (silt loam, WI) 

Desorption - Kfoc 

76.7 (silt loam, NE) 

95.7 (silt loam, LA) 

81.1 (silt loam, NE) 

58.2 (silt loam, WI) 

Terrestrial Field Dissipation HalfLife1

 

29.5 days (NE silty clay loam cropped 

with pre-emergent corn) 

451217-18 Acceptable 

Major degradation product: Desamino 

(Max 26% @ 59 days) 

24.9 days (WI silt loam soil cropped 

with pre-emergent corn) 

45121727 Acceptable 

Major degradation product: Desamino 

(Max 27% @ 61 days) 

1Half-lives were recalculated using PestDF (EFED, 2014) 

Transformation Products 

Table 6 summarizes the environmental fate properties of Desamino and N-methyl Desamino, 

while Appendix A provides additional detail on formation of transformation products in the 

environment, including structures.
10 

Table 6. Amicarbazone Degradates’ Environmental Fate Summary 

Parameter Value* Source 

(MRID) Study Status

N-Methyl Desamino 

Hydrolysis half-life1 

Stable - pH 4 @ 50 °C 

Stable - pH 7 @ 50 °C 

333 days (SFO) – pH 9 @ 20 °C 

13.6 days (SFO) – pH 9 @ 40 °C 

0.77 days (SFO) – pH 9 @ 60 °C 

48073601 Acceptable 

Aerobic soil metabolism halflife1 

@ 20 °C

Stable – clay loam soil, sandy loam 

soil, loamy sand soil, loam soil 48407501 Acceptable 

Adsorption – Kfoc

49.7 (silt loam, NE) 

45121733 Supplemental

49.0 (silt loam, LA) 

56.4 (silt loam, NE) 

34.3 (silt loam, WI) 

Desorption – Kfoc

89.4 (silt loam, NE) 

110.4 (silt loam, LA) 

101.2 (silt loam, NE) 

63.8 (silt loam, WI) 

Desamino 

Hydrolysis half-life 

Stable - pH 4 @ 50 °C 

Stable - pH 7 @ 50 °C 

Stable - pH 9 @ 50 °C

48237506 Acceptable 

Aerobic soil metabolism halflife1 

@ 20 °C

6230 days – clay loam soil 

1420 – sandy loam soil 

Stable – loamy sand soil 

758 days – loam soil 

48407502 Acceptable

Adsorption – Kfoc

39.2 (silt loam, NE) 

45121801 Supplemental

26.4 (silt loam, LA) 

42.3 (silt loam, NE) 

27.6 (silt loam, WI) 

Desorption – Kfoc

86.8 (silt loam, NE) 

96.7 (silt loam, LA) 

89.3 (silt loam, NE) 

53.3 (silt loam, WI) 
11 

Table 6. Amicarbazone Degradates’ Environmental Fate Summary 

Parameter Value* Source 

(MRID) Study Status

N-Methyl Desamino 

Hydrolysis half-life1 

Stable - pH 4 @ 50 °C 

Stable - pH 7 @ 50 °C 

333 days (SFO) – pH 9 @ 20 °C 

13.6 days (SFO) – pH 9 @ 40 °C 

0.77 days (SFO) – pH 9 @ 60 °C 

48073601 Acceptable 

Aerobic soil metabolism halflife1 

@ 20 °C

Stable – clay loam soil, sandy loam 

soil, loamy sand soil, loam soil 48407501 Acceptable 

Adsorption – Kfoc

49.7 (silt loam, NE) 

45121733 Supplemental

49.0 (silt loam, LA) 

56.4 (silt loam, NE) 

34.3 (silt loam, WI) 

Desorption – Kfoc

89.4 (silt loam, NE) 

110.4 (silt loam, LA) 

101.2 (silt loam, NE) 

63.8 (silt loam, WI) 

Decarboxamide 

Adsorption – Kfoc 13.4 (silt loam, NE) 

48237506 Supplemental

12.3(silt loam, LA) 

13.8 (silt loam, NE) 

9.4 (silt loam, WI) 

Desorption – Kfoc 68.0 (silt loam, NE) 

60.2 (silt loam, LA) 

81.5 (silt loam, NE) 

59.7 (silt loam, WI) 

1Half-lives were recalculated using PestDF (EFED, 2014) 

RECEPTORS 

Tables 7 and 8 provide a summary of the available aquatic and terrestrial toxicity data, 

respectively, using the most sensitive surrogate species tested to characterize the potential acute 

and chronic ecological effects of amicarbazone. In addition, the tables provide information on 

the available toxicity data for amicarbazone degradates. 
12 

Overall, the acute toxicity studies indicate that technical grade amicarbazone (amicarbazone 

TGAI) is practically non-toxic to adult honey bees, slightly toxic to mammals, and slightly toxic 

to practically non-toxic to birds. However, data from chronic toxicity studies show that longerterm exposure to amicarbazone TGAI and the two metabolites, desamino amicarbazone and Nmethyl desamino amicarbazone, results in adverse effects on growth and reproductive parameters 

in birds. In addition, exposure to the TGAI in mammalian parents and offspring resulted in 

reduced growth parameters. No data are available to characterize the effects of amicarbazone 

metabolites in mammals or insects; however, the bird reproduction studies indicate the 

metabolites are 6 to 38 times less toxic than the parent compound. No data with passerine birds 

are available; an acute oral passerine bird study (Guideline 850.2100) is needed to satisfy EPA 

guideline requirements. 

Tier 2 seedling emergence and vegetative vigor terrestrial plant studies with the amicarbazone 

formulated product MKH 3586 70 WG show that both monocots and dicots are sensitive to 

amicarbazone, with dicots appearing more sensitive. Studies with the amicarbazone metabolites 

(Desamino and N-methyl) exhibited some effects to terrestrial plants; however, both are 

approximately 2-fold less toxic than the parent compound. 

Acute aquatic toxicity studies demonstrate that amicarbazone TGAI is practically non-toxic to 

freshwater and estuarine/marine fish, slightly toxic to freshwater invertebrates, and slightly toxic 

to practically non-toxic to estuarine/marine invertebrates. Longer-term exposure of aquatic 

animals to amicarbazone produces adverse effects on growth parameters in freshwater fish and 

on growth and reproductive parameters in freshwater and estuarine/marine invertebrates. No 

data are available to characterize the effects of amicarbazone metabolites in aquatic animals but 

with the parent persistent and stable to hydrolysis, the metabolites are expected to have a 

minimal impact on aquatic animals in acidic or neutral surface waters. However, the alkaline 

hydrolysis metabolite, decarboxamide, may be formed in alkaline surface waters. No toxicity 

data for the alkaline metabolite, decarboxamide, are available; however, because current label 

language prohibiting applying on coarse-textured soils (sand, loamy sand and sandy loam soils), 

or on soils with pH >7.4, such as calcareous soils; data on the effect of the alkaline metabolite to 

aquatic organisms are not needed at this time. The decarboxamide would be treated as stable in 

alkaline aquatic systems, if an analysis in alkaline waters were needed. 

In the aquatic environment, amicarbazone appears to be particularly toxic to algae, but produces 

adverse effects on survival and growth in both algae and vascular plants. The results of a single 

study assessing the toxicity of the amicarbazone metabolite Desamino in Selenastrum 

capricornutum (a freshwater green algae), indicate that Desamino is 16-fold less toxic than the 

parent compound. 

A definitive NOAEC has not been established for chronic exposure to estuarine/marine 

invertebrates, which normally results in a presumption of risk for estuarine/marine invertebrates 

until available data show differently. In the absence of such data, EFED is not requiring a mysid 

chronic toxicity study to establish a definitive NOAEC because the lowest test concentration of 

2400 μg a.i./L in the study needs to be 320x more toxic to result in a chronic LOC exceedance 

when using the highest 21-day EEC of 7.5 μg a.i./L (EEC used in this calculation was obtained 
13 

from the August 30, 2010 risk assessment for new use on turf grasses; D384516), which is 

unlikely. 

Table 7. Toxicity Profile for Aquatic Species to Amicarbazone and its Degradates 

Species 

(scientific name) 

Study 

Type 

Test 

Material 

Toxicity 

Endpoint* 

(mg a.i./L) 

Study 

Classification

(MRID) 

Acute 

Toxicity 

Classification 

Freshwater Fish 

Lepomis 

macrochirus 

(Bluegill sunfish) 

Acute TGAI LC50 >128.5 Supplemental1

(45121804) 

Practically 

nontoxic 

Pimephales 

promelas (Fathead 

minnow) 

Chronic TGAI 

NOAEC = 7.3 

Based on reduced 

dry weight 

Acceptable 

(45121602) --- 

Freshwater Invertebrates 

Daphnia magna 

(Water flea) 

Acute TGAI EC50 = 40.8 Acceptable 

(45121808) Slightly toxic 

Chronic TGAI 

NOAEC = 0.73 

Based on reduced 

dry weight 

Acceptable 

(48071501) -- 

Estuarine/marine Fish 

Cyprinodon 

variegatus 

(Sheepshead 

minnow) 

Acute TGAI LC50 >118 Acceptable 

(45121806) 

Practically 

nontoxic 

Chronic TGAI 

NOAEC = 2.3 

No treatment 

related effects 

were observed 

Acceptable 

(48237510) -- 

Estuarine/marine Invertebrates 

Mysidopsis bahia 

(Mysid shrimp)

Acute TGAI LC50 = 109.7 Acceptable 

(45121810) 

Practically 

nontoxic 

Chronic TGAI 

NOAEC <2.4 

Based on reduced 

female body 

weight 

Supplemental2

(48407503) -- 

Aquatic Vascular Plants 

Lemna gibba

(Duckweed) 

Frond 

count TGAI 

EC50 = 0.21 Acceptable 

(45121805) -- 

NOAEC = 0.0406 

Aquatic Nonvascular Plants

Growth TGAI EC50 = 0.017 -- 
14 

Table 7. Toxicity Profile for Aquatic Species to Amicarbazone and its Degradates 

Species 

(scientific name) 

Study 

Type 

Test 

Material 

Toxicity 

Endpoint* 

(mg a.i./L) 

Study 

Classification

(MRID) 

Acute 

Toxicity 

Classification 

Skeletonema 

costatum 

(Marine diatom) 

NOAEC = 0.0057 Acceptable 

(45121818) 

Selenastrum 

capricornutum 

(Green algae) 

Growth TGAI EC50 = 0.084 Acceptable 

(45121820) -- NOAEC = 0.013 

Growth 

Degradate 

of TGAI 

(Desamino) 

EC50 >1.35 

Acceptable 

(45121827) -- NOAEC = 1.35 

* Animal LC50s/ EC50s and NOAECs are used as acute and chronic toxicity endpoints, respectively; while plant EC50s and 

NOAECs are used as non-listed and listed toxicity endpoints, respectively. 

1 Mean control fish weight of 0.43 g at test termination was less than the required initial weight range of 0.5 to 5 g. 

2 A NOAEC could not be determined for female dry weight, the most sensitive endpoint due to significant reductions at all 

treatment levels. 

Table 8. Toxicity Profile for Terrestrial Species to Amicarbazone and its Degradates.

Species 

(common name) Test Type Test 

Material 

Toxicity Endpoint 

(mg a.i./kg-bw or –

diet, μg a.i./bee, or 

lb a.i./A) 

Study 

Classification 

(MRID)

Acute 

Toxicity 

Classification 

Upland Game Birds and Waterfowl 

Colinus virginianus

(Northern bobwhite 

quail) 

TGAI 

LD50 1965 Supplemental2 

(45121811) Slightly toxic 

LC50 >5690 Acceptable 

(48237511) 

Practically 

nontoxic 

NOAEC 

27.1 

Reduced no. of 

viable embryos and 

% hatchling per 

eggs set 

Acceptable 

(45121819) -- 

Degradate 

of TGAI 

(Desamino)

NOAEC 

1030 

No effects seen at 

highest dose 

Acceptable 

(48237515) -- 

Degradate 

of TGAI 

(N-Methyl 

Desamino)

NOAEC 

413 

Reduced hatchling 

and survivor body 

weights 

Acceptable 

(48237514) -- 

Passerine Birds 
15 

Table 8. Toxicity Profile for Terrestrial Species to Amicarbazone and its Degradates.

Species 

(common name) Test Type Test 

Material 

Toxicity Endpoint 

(mg a.i./kg-bw or –

diet, μg a.i./bee, or 

lb a.i./A) 

Study 

Classification 

(MRID)

Acute 

Toxicity 

Classification 

No data TGAI LD50 No data No data No data 

Mammals 

Rattus norvegicus 

(Laboratory rat) TGAI 

LD50 1087 Acceptable 

(45121605) Slightly toxic 

NOAEC 

Offspring = 6.4/7.3 

mg/kg/day 

[6.4 mg/kg/day 

equivalent to 100 

mg/kg diet] 

Acceptable 

(45121625) -- 

Terrestrial Insects 

Apis mellifera

(Honeybee) TGAI 

Contact LD50 >200 Supplemental3

(45121816) 

Practically 

nontoxic 

Oral LD50 = 24.4 -- 

Seedling Emergence 

Monocot; Onion 

(Allium cepa) 

Growth TEP 

EC25 = 0.1 

Acceptable 

(45121821) -- 

EC05 = 0.0341 

[NOAEC = 0.126] 

Dicot; Sugar beet 

(Beta vulgaris) 

EC25 = 0.03 

NOAEC = 0.016 

Monocot; Wheat 

(Triticum astivum) 

Growth 

Deg. of TEP 

(N-Methyl 

Desamino)

EC25 >0.418 

Acceptable 

(48237517) -- 

NOAEC = 0.00493 

Dicot; Sugar beet 

(Beta vulgaris) 

EC25 = 0.0866 

EC05 = 0.00465 1 

[NOAEC = 0.146] 

Monocot; Ryegrass 

(Lolium perenne) 

Growth Deg. of TEP 

(Desamino) 

EC25 >0.38 

Acceptable 

(48237516) -- 

NOAEC = 0.0049 

Dicot; Cabbage 

(Brassica oleracea) 

EC25 = 0.16 

NOAEC = 0.061 

Vegetative Vigor 

Monocot: Onion 

(Allium cepa) Growth TEP 

EC25 = 0.026 

Acceptable 

(45121821) NOAEC = 0.016 -- 

Dicot; Buckwheat EC25 = 0.0037 
16 

Table 8. Toxicity Profile for Terrestrial Species to Amicarbazone and its Degradates.

Species 

(common name) Test Type Test 

Material 

Toxicity Endpoint 

(mg a.i./kg-bw or –

diet, μg a.i./bee, or 

lb a.i./A) 

Study 

Classification 

(MRID)

Acute 

Toxicity 

Classification 

(Fagopyrum 

esculentum) NOAEC = 0.002 

Monocot; Corn 

(Zea mays) 

Growth 

Deg. of TEP 

(N-Methyl 

Desamino)

EC25 >0.457 

Acceptable 

(48237518) -- 

NOAEC = 0.457 

Dicot; Sugar beet 

(Beta vulgaris) 

EC25 = 0.0251 

NOAEC = 0.00532 

Monocot; Wheat 

(Triticum astivum) 

Growth Deg. of TEP 

(Desamino) 

EC25 >0.30 

Acceptable 

(48237520) -- 

NOAEC = 0.019 

Dicot; Sugar beet 

(Beta vulgaris) 

EC25 = 0.318 

EC05 = 0.122 1 

[NOAEC <0.0057] 

1

 An EC05 is used when the NOAEC is below the lowest test concentration or above the EC25. 

2 A statistically reliable LD50 value could not be established or established with certainty. 

3

 The solvent used in the study was not a USEPA recommended solvent. 

Exposure Pathways of Concern 

The exposure pathways for amicarbazone and its transformation products may result in a wide 

range of potential aquatic and terrestrial exposure scenarios. For this problem formulation, the 

drinking water and inhalation pathways for birds and mammals were screened using the SIP 

(Screening Imbibition Program) and STIR (Screening Tool for Inhalation Risk) screening 

methods. STIR found the inhalation pathway not likely to be significant, but the SIP analysis 

identified exposure through drinking water alone to be a potential pathway of concern for birds 

and mammals (acute and chronic). This is primarily due to the water solubility of the compound 

and is a route of exposure that will be further analyzed in the forthcoming risk assessment. 

Drinking water exposure alone, according to the SIP model, is a potential pathway of concern for 

birds and mammals on an acute and chronic exposure basis. SIP is a screening (tier I) assessment 

used to determine whether there is a potential for a pathway of concern, which is intended to be 

evaluated in further developments of SIP. The following conservative assumptions were used to 

derive upper bound exposure estimates for drinking water alone: 1) solubility at the solubility 

limit of amicarbazone, 2) 100% of animal daily water needs come from drinking water, 3) the 

daily water need is equivalent to the daily water intake rate, 4) body weight for birds is 

equivalent to the smallest bird (i.e., 20 g) modeled in T-REX, and 5) body weight for mammals 

is equivalent to the largest mammal (i.e., 1000 g) modeled in T-REX. The upper bound exposure 

estimates will be refined further when the next version of SIP is developed. 
17 

Results of the SIP and STIR screening analyses have not been aggregated with all other exposure 

pathways (dietary, dermal, inhalation, or drinking water). The aggregate value may represent 

risks of concern for non-target animals beyond our current estimates. The risk characterization 

section of the future risk assessment will discuss the impact of these multiple routes of exposure 

on ecological risks and the degree of certainty associated with screening-level risk assessment 

conclusions. SIP and STIR are described in detail at 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm and the SIP and STIR model inputs 

and outputs for amicarbazone are available in Appendices B and C, respectively. 

 

ANALYSIS PLAN 

Ecological Risk Assessment 

Stressors of Concern 

Parent amicarbazone only will be considered in the risk assessment because: 1) a freshwater 

green algae study indicates the desamino metabolite is less toxic than parent; 2) four avian 

reproduction studies indicate the metabolites, desamino and N-methyl, are less toxic than the 

parent; 3) seedling emergence and vegetative vigor studies indicate the metabolites, desamino 

and N-methyl, are less toxic than the parent; and 4) labels restricting use on alkaline soils limit 

the potential formation of the metabolite decarboxamide, for which toxicity is not known . 

Measures of Exposure

In order to estimate risks of amicarbazone exposure to aquatic and terrestrial organisms, all 

exposure modeling and resulting risk conclusions will be made based on maximum application 

rates, application methods, and any mitigation measures specifically indicated on the label. The 

models that will be used to predict the estimated environmental concentrations (EECs) of 

amicarbazone are discussed on OPP’s model website.2

 These models include: SWCC, AgDrift, 

AgDisp, T-REX, and TerrPlant. 

Measure of Effects 

Ecological effects data are used as measures of direct and indirect effects to biological receptors. 

Data are typically obtained from registrant-submitted studies and from literature studies 

identified by ECOTOX. The ECOTOX database provides more ecological effects data in an 

attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity 

data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and 

wildlife. ECOTOX was created and is maintained by the U.S. EPA, Office of Research and 

Development, and the National Health and Environmental Effects Research Laboratory's MidContinent Ecology Division. 

Integration of Exposure and Effects 

 

2

 http://www.epa.gov/opp00001/science/models_pg.htm 
18 

Risk characterization is the integration of exposure and ecological effects to determine the 

potential ecological risk from the use of pesticides and the likelihood of direct and indirect 

effects to non-target organisms in aquatic and terrestrial habitats. For the assessment of risks, the 

risk quotient (RQ) method is used to compare exposure and measured toxicity values. EECs are 

calculated for acute and chronic concentrations and are compared to acute and chronic toxicity 

endpoints. The resulting RQs are then compared to the Agency’s Levels of Concern (LOCs) 

(USEPA 2004). These criteria will be used to indicate when amicarbazone use, as directed on the 

label, has the potential to cause adverse direct effects to non-target organisms. In addition, any 

available incident data will be considered (see below) as part of the risk characterization.

Endangered Species Assessments 

In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the 

National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department 

of Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks 

to listed species from pesticides. The Interim Approaches were developed jointly by the 

agencies in response to the National Academy of Sciences’ (NAS) recommendations and reflect 

a common approach to risk assessment shared by the agencies as a way of addressing scientific 

differences between the EPA and the Services. The NAS report outlines recommendations on 

specific scientific and technical issues related to the development of pesticide risk assessments 

that EPA and the Services must conduct in connection with their obligations under the 

Endangered Species Act (ESA) and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on November 

15, 2013. In addition, the EPA presented the joint Interim Approaches at the December 2013 

Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and 

Evaluation Group (SFIREG) meetings, and held a stakeholder workshop in April 2014, allowing 

additional opportunities for stakeholders to comment on the Interim Approaches. As part of a 

phased, iterative process for developing the Interim Approaches, the agencies will also consider 

public comments on the Interim Approaches in connection with the development of upcoming 

Registration Review decisions. The details of the joint Interim Approaches are contained in the 

white paper “Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy of Sciences April 2013 

Report,” dated November 1, 2013. 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, the ecological risk assessment supporting the proposed interim 

registration review decision for amicarbazone is not expected to contain a complete ESA 

analysis. Once the agencies have fully vetted the scientific methods necessary to complete risk 

assessments for endangered and threatened (listed) species and their designated critical habitats, 

these methods will be applied to subsequent analyses for amicarbazone as part of completing this 

registration review. 
19 

Endocrine Disruptor Screening Program 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints that may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its reregistration decision for amicarbazone, EPA reviewed these 

data and selected the most sensitive endpoints for relevant risk assessment scenarios from the 

existing hazard database. However, as required by FFDCA section 408(p), amicarbazone is 

subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list 

of chemicals identified for EDSP screening was published on June 14, 20133

 and includes some 

pesticides scheduled for registration review and chemicals found in water. Neither of these lists 

should be construed as a list of known or likely endocrine disruptors. 

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.4

Review of Incident Data

Three incident databases are available: 1) the Ecological Incident Information System v. 2.1.1 

(EIIS), maintained by EFED; 2) the Avian Incident Monitoring System (AIMS), maintained by 

 

3

 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals. 

4

 http://www.epa.gov/endo/ 
20 

the American Bird Conservancy; and, 3) the Incident Data System (IDS) maintained by OPP. 

These databases were searched on 6/1/15. 

The Ecological Incident Information System (EIIS) database was queried for incidents related to 

amicarbazone use. No incidents were reported in the EIIS database. 

A query of the aggregate Incident System (IDS) reported no incidents. 

The Avian Incident Monitoring System (AIMS), a database administered by the American Bird 

Conservancy, was queried for amicarbazone on 6/1/15 and there were no bird incidents reported. 

PRELIMINARY IDENTIFICATION OF DATA GAPS 

Environmental Fate 

Table 9 identifies the environmental fate studies by MRID that offer data for each Part 158 data 

requirement, as well as study classifications and whether or not further data are anticipated to be 

needed in order to support risk assessment for the amicarbazone registration review. 

Table 9. Submitted Environmental Fate Data for Amicarbazone and Data Needs 

OCSPP 

Guideline

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are 

data 

needed?

 Additional Comments 

835.2120 Hydrolysis 45121730 

48073601* 

48237506**

Acceptable 

Acceptable 

Acceptable 

No 

* N-methyl desamino 

degradate 

** Desamino degradate 

835.2240 Aqueous 

photolysis 45121803 Acceptable No 

835.2410 Soil photolysis 45121714 Supplemental No 

835.4100 Aerobic soil 

metabolism 

45121731 

48237507 

48407501* 

48407502**

Supplemental 

Acceptable 

Acceptable 

Acceptable 

No 

* N-methyl desamino 

degradate 

** Desamino degradate 

835.4200 Anaerobic soil 

metabolism 45121720 Unacceptable Yes 

Will be modeled as stable 

unless new data are 

submitted. 

835.4300 Aerobic aquatic 

metabolism 48237508 Unacceptable Yes 

Will be modeled as stable 

unless new data are 

submitted. 

835.4400 Anaerobic 

aquatic 

metabolism 

45121724 Supplemental Yes 

Will be modeled as stable 

unless new data are 

submitted. 
21 

Table 9. Submitted Environmental Fate Data for Amicarbazone and Data Needs 

OCSPP 

Guideline

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are 

data 

needed?

 Additional Comments 

835.1230 Adsorption/ 

desorption 

45121717 

45121719 

45121732 

45121733* 

45121801** 

45121802***

Acceptable 

Supplemental 

Supplemental 

Supplemental 

Supplemental 

Supplemental 

No 

* N-methyl desamino 

degradate 

** Desamino degradate 

*** Decarboxamide degradate

835.1410 Volatility – 

laboratory No data submitted No 

Low vapor pressure and 

Henry’s Law constant 

indicate volatilization is not 

likely. 

835.6100 Terrestrial field 

dissipation 

45121718 

45121727 

Acceptable 

Acceptable No 

835.7100 Prospective 

ground water 

study 

45938501 

45938502 

46049601 

46092401 

46145311 

46326001 

46670902 

46675101 

In review No 

835.6200 Aquatic field 

dissipation No data submitted No No aquatic uses 

850.1730 Fish 

bioconcentration No data submitted No Low log Kow indicates bioconcentration is not likely.

850.6100 Analytical 

method in soil 

45121728 

45121729 

(ILV) 

In review No 

850.6100 Analytical 

method in water 

45121725 

45121726 

45121715 

(ILV) 

In review No 

Ecological Effects 

Tables 10 and 11 identify the ecological effects studies, as well as study classifications, and 

whether or not further data are anticipated to be needed in order to support risk assessment for 

registration review. The rationale for the additional data that EFED recommends be requested is 

presented below. 

• Amicarbazone may cause exposure of pollinators visiting off-site plants that are 

contaminated by spray drift. A complete set of toxicity data for honey bee adults and 
22 

larvae have not been submitted for amicarbazone and are now needed under EPA’s recent 

policy on pollinator protection5. Thus, the following six Tier I and II honey bee studies, 

yet to be submitted for amicarbazone, are needed: 

o Honeybee larval acute oral toxicity study (following OECD 237) 

o Honeybee adult 10-day chronic oral (special study) 

o Honeybee larval repeated dose study (special study renamed as honeybee larval 

chronic oral toxicity study) 

o Field testing for pollinators (OCSPP 850.3040, Tier III) 

o Field trial of residues in pollen and nectar (special study, Tier II) 

o Semi-field testing for pollinators (special study, Tier II). 

Note that it is possible to conduct the larval chronic oral study in such a way as to derive 

both an LD50 (acute endpoint of interest) and a NOAEC (chronic endpoint of interest) 

from a single study. If the chronic larval toxicity study is conducted in such a way that it 

derives both an LD50 and NOAEC, then a separate acute larval toxicity study is not 

needed. For pollinator studies without finalized OECD guidelines, protocols should be 

submitted for EPA review and comment prior to study initiation. 

The need for higher Tier semi-field and full field pollinator studies for amicarbazone will 

be determined after review of the Tier I studies. 

• Acceptable acute avian acute oral toxicity (Guideline 850.2100) data for a passerine 

species exposed to amicarbazone, per the 40 CFR Part 158 data requirements, are needed. 

Although the available bobwhite quail study indicates amicarbazone has low toxicity to 

upland game bird species, it is uncertain whether passerines may be more or less sensitive 

to this chemical as a result of their higher metabolic rate, smaller size, and differing 

metabolic pathways. Given the reproductive effects of survivor and hatchling body 

weights and viable embryos observed in birds, EFED cannot preclude the potential risk to 

passerines. An avian oral toxicity study is needed for a passerine species. 

 

5

 (Guidance for Assessing Pesticide Risks to Bees, 06.23.2014; signed by Donald Brady, Director, EFED; 

http://www2.epa.gov/sites/production/files/2014-

06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf) 
23 

Table 10. Submitted Aquatic Ecological Effects Data for Amicarbazone 

OCSPP 

Guideline

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are data 

Needed for 

Assessment? 

Justification and 

Assumptions 

EPA will Make 

in Absence of 

Data 

850.1010 

Freshwater 

invertebrate 

acute toxicity 

45121808 Acceptable No -- 

850.1025 

850.1035 

Estuarine/Marine 

invertebrate 

acute toxicity 

45121809 

45121810 

Supplemental 

Acceptable No -- 

850.1075 Freshwater fish 

acute toxicity 

45121804 

45121807 

Supplemental 

Supplemental No -- 

850.1075 

Estuarine/Marine 

fish acute 

toxicity 

45121806 Acceptable No -- 

850.1300 

Freshwater 

invertebrate life 

cycle 

45121822 

48071501 

Supplemental 

Acceptable No -- 

850.1350 

Estuarine/Marine 

invertebrates life 

cycle 

45121601 

48407503 

Supplemental 

Supplemental No 

A definitive 

NOAEC was not 

established; 

however, EFED 

is not requiring 

the data because 

toxicity needs to 

be 320x more 

toxic to result in 

a LOC 

exceedance. 

850.1400 

Estuarine/Marine 

fish early-life 

stage 

48237510 Acceptable No -- 
24 

Table 10. Submitted Aquatic Ecological Effects Data for Amicarbazone 

OCSPP 

Guideline

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications

Are data 

Needed for 

Assessment? 

Justification and 

Assumptions 

EPA will Make 

in Absence of 

Data 

850.1400 Freshwater fish 

early-life stage 45121602 Acceptable No -- 

850.1500 Fish life cycle (None) (N/A) No 

No LOC 

exceedances were 

observed with 

aquatic 

organisms thus a 

FLC study is not 

needed. 

850.1735 

Benthic 

invertebrates 

(acute) 

No data -- No Not triggered per 

40 CFR Part 158 

based on 

chemical 

characteristics 850.1740 

Benthic 

invertebrates 

(chronic) 

No data -- No 

850.4400 

Aquatic plant 

growth: Vascular 

plants 

45121805 Acceptable No -- 

850.4500 Aquatic Plant 

Growth: Algal 

45121812 

45121818 

45121820 

(TGAI) 

Acceptable 

Acceptable 

Acceptable No 

-- 

45121827 

(Desamino) Acceptable No 

850.4550 

Aquatic Plant 

Growth: 

Cyanobacteria 

45121825 Acceptable No -- 
25 

Table 11. Submitted Terrestrial Ecological Effects Data for Amicarbazone and Data Needs

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed for 

assessment?

Current Additional 

Data Need 

850.2100 Avian oral 

toxicity 45121811 Supplemental Yes 

Without data, risk 

would be presumed for 

passerine birds, 

including listed species.

850.2200 Avian dietary 

toxicity 

45121815 

48237511 

Acceptable 

Acceptable No -- 

850.2300 Avian 

reproduction 

45121814 

45121819 

48237512 

48237513 

48237514 

48237515 

Acceptable 

Acceptable 

Acceptable 

Supplemental 

Acceptable 

Acceptable 

No -- 

Nonguideline Avian 

inhalation (None) (N/A) No 

The STIR model 

indicates exposure 

through inhalation is not 

a concern for birds. 

850.3020 

Adult honey 

bee acute 

contact 

toxicity 45121816 

Supplemental No -- 

SS 

Adult honey 

bee acute oral 

toxicity 

Supplemental No 

850.3030 

Honey bee 

residue on 

foliage 

No data No data No 

Not triggered. The bee 

acute contact LD50 of 

>200 μg a.i./L is above 

11 μg a.i./L, the 

practically nontoxic 

toxicity classification 

for bees. 

850.3040 Field testing 

for pollinators No data No data Yes Pollinator Tier I, II 

and III studies with 

honeybees are 

necessary to satisfy 

data requirements. 

SS 

Larval honey 

bee chronic 

oral toxicity 

No data No data Yes 
26 

Table 11. Submitted Terrestrial Ecological Effects Data for Amicarbazone and Data Needs

OCSPP 

Guideline

Data 

Requirement

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Are data 

needed for 

assessment?

Current Additional 

Data Need 

SS 

Adult honey 

bee chronic 

oral toxicity 

No data No data Yes 

Without data, risk 

would be presumed for 

pollinators, including 

listed species.

SS 

Larval honey 

bee acute 

toxicity 

No data No data Yes 

SS 

Field testing 

of residues in 

pollen and 

nectar 

No data No data Yes 

SS 

Semi-field 

testing for 

pollinators 

No data No data Yes 

850.4100 

Tier I or II 

seedling 

emergence 

45121821 

45121826 

48237516 

48237517 

Acceptable 

Supplemental 

Acceptable 

Acceptable 

No 

-- 

850.4150 

Tier I or II 

vegetative 

vigor 

45121821 

45121826 

48237518 

48237519 

48237520 

Acceptable 

Supplemental 

Acceptable 

Acceptable 

Acceptable 

No 

REFERENCES: 

USEPA 2010. Section 3 Registration for New Use of Amicarbazone on Turf Grasses Grown 

Nationwide. D384516. August 30, 2010. 

USEPA 2005. Environmental Fate and Effect Division’s Risk Assessment for the Section 3 New 

Active Ingredient Registration for Amicarbazone (CAS Number 129909-90-6). D288631. 

April 11, 2005. 

USEPA, PMRA and CDPR, 2014. Guidance for Assessing Pesticide Risks to Bees. Office of 

Pesticide Programs, USEPA, Washington D.C. Health Canada Pest Management 

Regulatory Agency, Ottawa, ON, Canada. California Department of Pesticide Regulation, 

Sacramento, CA. June 23, 2014. 
27 

OPPIN BIBLIOGRAPHY: 

Environmental Fate 

835.2120 Hydrolysis 

MRID Citation Reference

45121730 Widmer, S.; Bloomberg, A.; Dement, T. (1998) Hydrolysis of (Triazolinone-3-

(carbon 14))MKH 3586 in Aqueous Sterile Buffer Solutions: Lab Project 

Number: 107106: M6022402. Unpublished study prepared by Bayer Corp. 37 

p. 

835.2130 Hydrolysis as a function of pH at 25 C 

MRID Citation Reference

48073601 Schick, M. (2010) Hydrolysis of [Carbon 14]N-Methyl Desamino Amicarbazone 

at pH 4, 7 and 9. Project Number: 1913W, 1913W/1. Unpublished study 

prepared by PTRL West, Inc. 111 p. 

48237506 Schick, M. (2010) Hydrolysis of (Carbon 14)Desamino Amicarbazone at pH 4, 

7 and 9. Project Number: 1912W//1912W/1, 1912W/OCR. Unpublished study 

prepared by PTRL West, Inc. 69 p. 

835.2240 Photodegradation-water 

MRID Citation Reference

45121803 Ripperger, R.; Bloomberg, A.; Puhl, R. (1999) Photolysis of (Triazolinone-3-

(carbon 14))MKH 3586 in Sterile Aqueous Buffer (pH 7) and in Natural Water: 

Lab Project Number: 107107: M6082401. Unpublished study prepared by 

Bayer Corp. 77 p. 

835.2410 Photodegradation-soil 

MRID Citation Reference

45121714 Bloomberg, A.; Dement, T.; Helfrich, K. et al. (1999) Photolysis of 

(Triazolinone-3-(carbon 14))MKH 3586 on Silt Loam: Lab Project Number: 

107108: M6082101. Unpublished study prepared by Bayer Corp. and 

Springborn Labs. 65 p. 
28 

835.4100 Aerobic soil metabolism 

MRID Citation Reference

45121720 Marco da Silva, P. (1999) Aerobic Soil Metabolism of MKH 3586-triazolinone3-(carbon 14) on Three Brazilian Soils: Lab Project Number: 109246: 

M6042102: RF-E12.01/99. Unpublished study prepared by Bioagri 

Laboratorios Ltda. 65 p. 

45121731 Leimkuehler, W.; Billesbach, K. (1998) Aerobic Soil Metabolism of 

(triazolinone-5-(carbon 14))MKH 3586: Lab Project Number: M6042101: 

106966. Unpublished study prepared by Bayer Corp. 42 p. 

48237507 Shepler, K. (2010) Aerobic Soil Metabolism of [Carbon 14] Amicarbazone in 

Four Soils. Project Number: 1889W/1, 1889W/OCR. Unpublished study 

prepared by PTRL West, Inc. 202 p. 

48407501 Shepler, K. (2010) Aerobic Soil Metabolism of [Carbon 14]N-Methyl Desamino 

Amicarbazone in Four Soils. Project Number: 1891W/1. Unpublished study 

prepared by PTRL West, Inc. 171 p. 

48407502 Shepler, K. (2010) Aerobic Soil Metabolism of [Carbon 14]Desamino 

Amicarbazone in Four Soils. Project Number: 1890W/1. Unpublished study 

prepared by PTRL West, Inc. 188 p. 

835.4300 Aerobic aquatic metabolism 

MRID Citation Reference

45121724 Kelley, I.; Smith, D. (1997) Anaerobic Aquatic Metabolism of (Triazolinone-5-

(carbon 14))MKH 3586: Lab Project Number: 107318: M6042401. Unpublished 

study prepared by Bayer Corp. 34 p. 

48237508 Schick, M. (2010) Aerobic Aquatic Metabolism of [Carbon 14]Amicarbazone in 

Water/Sediment Systems.. Project Number: 1914W/1, 1914W/OCR. 

Unpublished study prepared by PTRL West, Inc. 133 p. 

835.1230 Adsorption/desorption 

MRID Citation Reference

45121717 Harbin, A.; Bloomberg, A.; Dement, T. et al. (1999) Leaching Potential of Aged 

(Triazolinone-3-(carbon 14)) MKH 3586 Residues in Coly Loam: Lab Project 

Number: 107109: M6092101. Unpublished study prepared by Bayer Corp. 60 

p. 

45121719 Marco da Silva, P. (1999) Adsorption/Desorption of MKH 3586-triazolinone-3-

(carbon 14) on Three Brazilian Soils: Lab Project Number: RF-E3.01/99: 

109209: M6182106. Unpublished study prepared by Bioagri Laboratorios Ltda. 

39 p. 
29 

45121732 Hein, W.; Bloomberg, A. (1999) Adsorption/Desorption of MKH 3586-

triazolinone-3-(carbon 14) in Four Soil Types: Lab Project Number: M6182104: 

108714: SLFA--BAC13. Unpublished study prepared by Staatliche Lehr-und 

Forschungsanstalt fur Landwirtschaft. 78 p. 

45121733 Hein, W.; Bloomberg, A. (1999) Adsorption/Desorption of 4-Methyl MKH 3594-

triazolinone-3-(carbon 14), an MKH 3586 Metabolite, in Four Soil Types: Lab 

Project Number: 108716: SLFA--BAC12: M6182103. Unpublished study 

prepared by Staatliche Lehr-und Forschungsanstalt fur Landwirtschaft. 72 p. 

45121801 Hein, W.; Bloomberg, A. (1999) Adsorption/Desorption of MKH 3594-

triazolinone-3-(carbon 14), an MKH 3586 Metabolite, in Four Soil Types: Lab 

Project Number: M6182102: 108715: SLFA-BAC11. Unpublished study 

prepared by Staatliche Lehr-und Forschungsanstalt fur Landwirtschaft. 76 p. 

45121802 Hein, W.; Bloomberg, A. (1999) Adsorption/Desorption of Decarboxamide MKH 

3594, an MKH 3586 Metabolite, in Four Soil Types: Lab Project Number: 

M6182105: SLFA-BAC14: 108717. Unpublished study prepared by Staatliche 

Lehr-und Forschungsanstalt fur Landwirtschaft. 78 p. 

 

835.1230 Adsorption/desorption

MRID Citation Reference

45121717 Harbin, A.; Bloomberg, A.; Dement, T. et al. (1999) Leaching Potential of Aged 

(Triazolinone-3-(carbon 14)) MKH 3586 Residues in Coly Loam: Lab Project 

Number: 107109: M6092101. Unpublished study prepared by Bayer Corp. 60 

p. 

835.6100 Terrestrial field dissipation 

MRID Citation Reference

45121715 Bauer, M. (1999) Independent Laboratory Validation of the Methods Described 

in Bayer Reports Nos. 108821 and 107949: Analytical Methods for the 

Determination of Residues of MKH 3586 and Three Metabolites in Water by 

High-Performance Liquid Chromatography Tandem Mass Spectrometry 

(LC/MS/MS): Lab Project Number: M6112401: 108829: N053275A. 

Unpublished study prepared by Battelle. 66 p. 

45121716 Wujcik, C.; Kelley, I.; Smith, D. (1999) Freezer Stability of MKH 3586 and its 

Metabolites Desamino MKH 3586, N-Methyl Desamino MKH 3586, and 

Decarboxamide MKH 3586 in Soil: Lab Project Number: 109468: M6132101. 

Unpublished study prepared by Bayer Corp. 80 p. 

45121718 Bloomberg, A.; Jordan, N.; Wiedmann, J. (1999) Terrestrial Field Dissipation of 

MKH 3586 in Nebraska Soil, 1996: Lab Project Number: 108920: 010193: 

98BAY.REP. Unpublished study prepared by Bayer Research Farm, A &L 

Great Lakes Lab. and Enviro-Test Labs. 186 p. 
30 

45121723 Kelley, I.; Manske, M. (1997) The Stability of MKH 3586 and its Metabolites 

MKH 3594 and N-Methyl MKH 3594 in Groundwater Stored under Refrigerated 

Conditions: Lab Project Number: 107127: M6132401. Unpublished study 

prepared by Bayer Corp. 36 p. 

45121727 Bloomberg, A.; Jordan, N.; Wiedmann, J. (1999) Terrestrial Field Dissipation of 

MKH 3586 in Wisconsin Soil, 1996: Lab Project Number: 010194: 

98BAY07.REP: 108733. Unpublished study prepared by AGSTAT, Enviro-Test 

Labs and Bayer Corp. 197 p. 

45121728 Bloomberg, A.; Lam, C.; Nelson, S. et al. (1998) Validation of the Analytical 

Method for the Determination of MKH 3586 and Three Metabolites in 

Wisconsin Soil by High Performance Liquid Chromatography Tandem Mass 

Spectrometry (LC/MS/MS): Lab Project Number: 98-B-67: M6022101: 108733-

1. Unpublished study prepared by Enviro-Test Labs. 112 p. 

45121729 Bauer, M. (1999) Independent Method Validation of Bayer Method 

MKH3586.mth 1 (Bayer Report No. 108733-1): Analytical Method for the 

Determination of Residues of MKH 3586 and Three Metabolites in Soil by High 

Performance Liquid Chromatography Tandem Mass Spectrometry 

(LC/MS/MS): Lab Project Number: 109105: M6112103: N053274A. 

Unpublished study prepared by Battelle. 63 p. 

860.1900 Field rotational crop 

MRID Citation Reference

45121704 Krolski, M.; Bosnak, L. (1999) The Accumulation of (Triazolinone-3-(carbon 

14))MKH 3586 Residues in Confined Rotational Crops: Lab Project Number: 

M6051601: 109220. Unpublished study prepared by Bayer Corp. 202 p. 

{OPPTS 860.1850} 

835.7100 Ground water-small prospective 

MRID Citation Reference

45121722 Pangilinan, N.; Wujcik, C.; Kelley, I. et al. (1999) Refrigerator Stability of 

Decarboxamide 3586, a Metabolite of MKH 3586, in Groundwater Addendum 

to: The Stability of MKH 3586 and its Metabolites MKH 3594 and N-Methyl 

MKH 3594 in Groundwater Stored under Refrigerated Conditions: Lab Project 

Number: 107127-1: M6132401. Unpublished study prepared by Bayer Corp. 35 

p. 

45121725 Heitkamp, J.; Dyer, D. (1999) Determination of MKH 3586 and Two 

Degradates (desamino-MKH 3586 and 4-methyl-desamino-MKH 3586) in 

Water by High-Performance Liquid Chromatography Tandem Mass 

Spectrometry (LC-MS/MS): Lab Project Number: 108821: M6122401: 

43042/43043. Unpublished study prepared by Bayer Corp. 38 p. 

45121726 Liemkuehler, W.; Widmer, S.; Billesbach, K. (1999) Analytical Method for the 

Determination of Decarboxamide MKH 3586 in Groundwater by High-
31 

Performance Liquid Chromatography--Tandem Mass Spectrometry: Lab 

Project Number: 107949. Unpublished study prepared by Bayer Corp. 28 p. 

45938501 Dyer, D.; Helfrich, K. (2000) Amicarbazone (MKH 3586)--Small-Scale 

Prospective Ground-Water Monitoring Study; Corn in Minden, Nebraska, 1994: 

Lab Project Number: TMN-138: 109732. Unpublished study prepared by Bayer 

Corporation, ABC Laboratories and LFR Levine-Fricke, Inc. 72 p. 

45938502 Helfrich, K.; Dyer, D. (2000) Amicarbazone (MKH 3586)--Small-Scale 

Prospective Ground-Water Monitoring Study; Corn in Shelton, Nebraska, 1994: 

Lab Project Number: TMN-137: 109731. Unpublished study prepared by Bayer 

Corporation, ABC Laboratories and LFR Levine-Fricke, Inc. 76 p. 

46049601 Dyer, D. (2003) Amicarbazane - Small-Scale Prospective Ground-Water 

Monitoring Study, Corn in Minden, Nebraska, 1994: Progress Report - July 

2003. Project Number: M6212402, TMN/138. Unpublished study prepared by 

Bayer Corp. 90 p. 

46092401 Dyer, D.; Lewis, T. (2003) Amicarbazone - Small-Scale Prospective GroundWater Monitoring Study, Corn in Shelton, Nebraska, 1994: Progress Report - 

August 2003. Project Number: M6212401, TMN/137, G200636. Unpublished 

study prepared by Bayer Corp., Analytical Bio-Chemistry Labs., Inc and 

Levine-Fricke, Inc. 250 p. 

46145311 Lewis, T.; Newcombe, A. (2003) Small-Scale Prospective Groundwater Study 

of Amicarbazone (MKH3586) in Hall County, Nebraska: Final Field Phase 

Report. Project Number: TMN/137, M6212401, 004/11213/00. Unpublished 

study prepared by Levine-Fricke, Inc. and Bayer Corp. and A & L Great Lakes 

Laboratories. 247 p. 

46326001 Helfrich, K.; Dyer, D. (2004) Amicarbazone (MKH 3586) -- Small-Scale 

Prospective Ground-Water Monitoring Study, Shelton, Nebraska, 1994-2000. 

Project Number: M6212401, 94P/121/I, 42427. Unpublished study prepared by 

Bayer Corp. and Levine-Fricke, Inc. and A & L Great Lakes Laboratories. 433 

p. 

46670902 Newcombe, A.; Dyer, D. (2005) Amicarbazone (MKH 3586) - Small-Scale 

Prospective Groundwater Monitoring Study, Minden, Nebraska, 1994-2004. 

Project Number: M6212402. Unpublished study prepared by Bayer Corp. 446 

p. 

46675101 Newcombe, A.; Dyer, D.; Helfrich, K. (2005) Amicarbazone (MKH 3586) - 

Small-Scale Prospective Groundwater Monitoring Study, Shelton, Nebraska, 

1994-2000. Project Number: M6212401. Unpublished study prepared by Bayer 

Cropscience LP. 352 p. 

Eco Effects 

850.2100 Avian Single Dose Oral Toxicity 

MRID Citation Reference
32 

45121811 Hancock, G. (1999) MKH 3586 Technical: An Acute Oral LD(50) with Northern 

Bobwhite: Lab Project Number: 108742: M6711701. Unpublished study prepared 

by Bayer Corp. 33 p. 

850.2200 Avian Dietary Toxicity 

MRID Citation Reference

45121815 Hancock, G. (1999) Technical MKH 3586: A Subacute Dietary LC(50) with 

Mallards: Lab Project Number: 108815: M6720801. Unpublished study prepared 

by Bayer Corp. 49 p. 

45121823 Bowers, L.; Stoughton, T. (1999) Technical MKH 3586: A Subacute Dietary 

LC(50) with Northern Bobwhite: Lab Project Number: M6721701: 109211. 

Unpublished study prepared by Bayer Corp. 53 p. 

45139603 Bowers, L.; Stoughton, T. (1999) Technical MKH 3586: A Subacute Dietary LC 

50 with Northern Bobwhite: Lab Project Number: M6721701: 109211. 

Unpublished study prepared by Bayer Corporation. 53 p. 

48237511 Hubbard, P.; Martin, K.; Beavers, J. (2009) Amicarbazone (MKH 3586): A Dietary 

LC50 Study with the Northern Bobwhite. Project Number: 443/126, 

443/126/OCR. Unpublished study prepared by Wildlife International Ltd. 77 p. 

850.2300 Avian Reproduction 

MRID Citation Reference

45121814 Martin, K.; Beavers, J.; Jaber, M. et al. (1999) MKH 3586 Technical: A 

Reproduction Study with the Mallard (Anas platyrhynchos): Lab Project Number: 

109202: 149-178. Unpublished study prepared by Wildlife International, Ltd. 184 

p. 

45121819 Gallagher, S.; Martin, K.; Jaber, M. et al. (1999) MKH 3586 Technical: A 

Reproduction Study with the Northern Bobwhite (Colinus virginianus): Lab 

Project Number: 109203: 149-177. Unpublished study prepared by Wildlife 

International, Ltd. 180 p. 

45139601 Gallagher, S.; Martin, K.; Beavers, J. et al. (1999) MKH 3586 Technical: A 

Reproduction Study with the Northern Bobwhite (Colinus virginianus): Lab 

Project Number: 149-177: 109203: 149/072498/QR.WC/SUB. Unpublished study 

prepared by Wildlife International, Ltd. 180 p. 

48237512 Temple, D.; Martin, K.; Beavers, J.; et al. (2010) Desamino Amicarbazone: A 

Reproduction Study with the Mallard: Final Report. Project Number: 443/125, 

443/125/OCR. Unpublished study prepared by Wildlife International Ltd. 197 p. 

48237513 Temple, D.; Martin, K.; Beavers, J.; et al. (2010) N-Methyl Desamino 

Amicarbazone: A Reproduction Study with the Mallard: Final Report. Project 

Number: 443/121, 443/121/OCR. Unpublished study prepared by Wildlife 

International Ltd. 198 p. 
33 

48237514 Temple, D.; Martin, K.; Beavers, J.; et al. (2010) N-Methyl Desamino 

Amicarbazone: A Reproduction Study with the Northern Bobwhite: Final Report. 

Project Number: 443/120, 443/120/OCR. Unpublished study prepared by Wildlife 

International Ltd. 208 p. 

48237515 Temple, D.; Martin, K.; Beavers, J. ; et al. (2010) Desamino Amicarbazone: A 

Reproduction Study with the Northern Bobwhite: Final Report. Project Number: 

443/124, 443/124/OCR. Unpublished study prepared by Wildlife International Ltd. 

205 p. 

850.1075 Acute Toxicity to Freshwater Fish 

MRID Citation Reference

45121804 Bowers, L.; Lam, C. (1999) Acute Toxicity of MKH 3586 Technical to the Bluegill 

(Lepomis macrochirus) Under Static Conditions: Lab Project Number: 108803: 

M6810301. Unpublished study prepared by Bayer Corp. 31 p. 

45121807 Bowers, L.; Franks, J. (1997) Acute Toxicity of MKH 3586 Technical to the 

Rainbow Trout (Oncorhynchus mykiss) Under Static Conditions: Lab Project 

Number: 107803: M6812201. Unpublished study prepared by Bayer Corp. 28 p. 

45121806 Bowers, L.; Franks, J. (1997) Acute Toxicity of MKH 3586 Technical to the 

Sheepshead Minnow (Cyprinodon variegatus) Under Static Conditions: Lab 

Project Number: 107744: M6832801. Unpublished study prepared by Bayer 

Corp. 29 p. 

850.1010 Acute Toxicity to Freshwater Invertebrates 

MRID Citation Reference

45121808 Bowers, L. (1998) Acute Toxicity of MKH 3586 Technical to the Waterflea 

(Daphnia magna) Under Static Conditions: Lab Project Number: M6820701: 

107912. Unpublished study prepared by Bayer Corp. 28 p. 

850.1025 & 850.1035 Acute Toxicity to Estuarine/Marine 

Invertebrates 

MRID Citation Reference

45121809 Palmer, S.; Krueger, H. (1998) MKH 3586 Technical: A 96-Hour Shell Deposition 

Test with the Eastern Oyster (Crassostrea virginica): Lab Project Number: 149-

108: 108113. Unpublished study prepared by Wildlife International Ltd. 44 p. 
34 

45121810 Palmer, S.; Krueger, H. (1998) MKH 3586 Technical: A 96-Hour Flow-Through 

Acute Toxicity Test with the Saltwater Mysid (Mysidopsis bahia): Lab Project 

Number: 149A-107: 108107. Unpublished study prepared by Wildlife 

International Ltd. 44 p. 

850.1300 Aquatic Invertebrate Life Cycle Study 

MRID Citation Reference

45121822 Hall, A.; Lam, C. (1999) Chronic Toxicity of MKH 3586 Technical to the Waterflea 

(Daphnia magna) Under Static Renewal Conditions: Lab Project Number: 

M6840701: 108454. Unpublished study prepared by Bayer Corp. 50 p. 

48071501 Minderhout, T.; Kendall, T.; Krueger, H. (2010) Amicarbazone (MKH 3586): A 

Flow-Through Life-Cycle Toxicity Test with the Cladoceran (Daphnia magna). 

Project Number: 443A/141. Unpublished study prepared by Wildlife International, 

Ltd. 81 p. 

850.1350 Mysid Chronic Toxicity test 

MRID Citation Reference

45121601 Drottar, K.; Krueger, H. (1998) MKH Technical: A Flow-Through Life-Cycle 

Toxicity Test with Saltwater Mysid (Mysidopsis bahia): Lab Project Number: 

149A-109: 108109. Unpublished study prepared by Wildlife International Ltd. 58 

p. 

48407503 Drottar, K.; Krueger, H. (2011) MKH 3586 Technical: A Flow-Through Life-Cycle 

Toxicity Test with the Saltwater Mysid (Mysidopsis bahia). Project Number: 

443A/146. Unpublished study prepared by Wildlife International, Ltd. 80 p. 

850.1400 Fish early-life stage toxicity test 

MRID Citation Reference

48237510 Minderhout, T.; Kendall, T.; Krueger, H. (2010) AMICARBAZONE (MKH 3586): 

An Early Life-Stage Toxicity Test with the Sheephead Minnow (Cyprinodon 

variegatus). Project Number: 443A/142A, 443A/142A/OCR. Unpublished study 

prepared by Wildlife International Ltd. 90 p. 

45121602 Drottar, K.; Krueger, H. (1999) MKH 3586 Technical: An Early Life-Stage Toxicity 

Test with Fathead Minnow (Pimephales promelas): Lab Project Number: 149A115: 108949. Unpublished study prepared by Wildlife International Ltd. 76 p. 

850.4100 Seedling emergence 
35 

MRID Citation Reference

45121821 Bowers, L. (2000) Tier 2 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 3586 70WG Formulation: Lab Project Number: 

109249: M6201601: M6201602. Unpublished study prepared by Bayer Corp. 155 

p. 

45121826 Bowers, L.; Lam, C.; Dollinger, M. (2000) Tier 2 Seedling Emergence and 

Vegetative Vigor Nontarget Phytotoxicity Study Using MKH 3594 (a Metabolite of 

MKH 3586): Lab Project Number: 109480. Unpublished study prepared by Bayer 

Corp. 83 p. 

45139602 Bowers, L. (2000) Tier 2 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 3586 70WG Formulation: Lab Project Number: 

M6201601: M6201602: 109249. Unpublished study prepared by Bayer 

Corporation. 155 p. 

48237516 Porch, J.; Krueger, H.; Kendall, T. (2010) Desamino Amicarbazone: A Toxicity 

Test to Determine the Effects of the Test Substance on Seeding Emergence of 

Ten Species of Plants: Final Report. Project Number: 443/127, 443/127/OCR. 

Unpublished study prepared by Wildlife International Ltd. 109 p. 

48237517 Porch, J.; Krueger, H.; Kendall, T. (2010) N-Methyl Desamino Amicarbazone: A 

Toxicity Test to Determine the Effects of the Test Substance on Seedling 

Emergence of Ten Species of Plants: Final Report. Project Number: 443/128, 

443/128/OCR. Unpublished study prepared by Wildlife International Ltd. 107 p. 

850.4150 Vegetative vigor 

MRID Citation Reference

45121821 Bowers, L. (2000) Tier 2 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 3586 70WG Formulation: Lab Project Number: 

109249: M6201601: M6201602. Unpublished study prepared by Bayer Corp. 

155 p. 

45121826 Bowers, L.; Lam, C.; Dollinger, M. (2000) Tier 2 Seedling Emergence and 

Vegetative Vigor Nontarget Phytotoxicity Study Using MKH 3594 (a Metabolite 

of MKH 3586): Lab Project Number: 109480. Unpublished study prepared by 

Bayer Corp. 83 p. 

45139602 Bowers, L. (2000) Tier 2 Seedling Emergence and Vegetative Vigor Nontarget 

Phytotoxicity Study Using MKH 3586 70WG Formulation: Lab Project Number: 

M6201601: M6201602: 109249. Unpublished study prepared by Bayer 

Corporation. 155 p. 

48237518 Porch, J.; Krueger, H.; Kendall, T. (2010) N-Methyl Desamino Amicarbazone: A 

Toxicity Test to Determine the Effects of the Test Substance on Vegetative 

Vigor of Ten Species of Plants: Final Report. Project Number: 443/131, 

443/131/OCR. Unpublished study prepared by Wildlife International Ltd. 156 p. 

48237519 Porch, J.; Krueger, H.; Kendall, T. (2010) Amicarbazone 70 WDG 

(Amicarbazone DF): A Toxicity Test to Determine the Effects of the Test 

Substance on Vegetative Vigor of Sugarbeet and Tomato: Final Report. Project 
36 

Number: 443/129, 443/129/OCR. Unpublished study prepared by Wildlife 

International Ltd. 68 p. 

48237520 Porch, J.; Krueger, H.; Kendall, T. (2010) Desamino Amicarbazone: A Toxicity 

Test to Determine the Effects of the Test Substance on Vegetative Vigor of Ten 

Species of Plants: Final Report. Project Number: 443/130, 443/130/OCR. 

Unpublished study prepared by Wildlife International Ltd. 156 p. 

850.4400 Aquatic plant toxicity test using Lemna spp. 

MRID Citation Reference

45121805 Bowers, L.; Lam, C. (1999) Toxicity of MKH 3586 Technical to Lemna gibba G3: 

Lab Project Number: 108940: M6883701. Unpublished study prepared by Bayer 

Corp. 34 p. 

 

850.4500 Algal Toxicity 

MRID Citation Reference

45121812 Bowers, L.; Lam, C. (1999) Toxicity of MKH 3586 Technical to the Freshwater 

Diatom Navicula pelliculosa: Lab Project Number: M6883401: 109133. 

Unpublished study prepared by Bayer Corp. 39 p. 

45121818 Lam, C.; Bowers, L. (1999) Toxicity of MKH 3586 Technical to the Marine 

Diatom Skeletonema costatum: Lab Project Number: 109125: M6883601. 

Unpublished study prepared by Bayer Corp. 35 p. 

45121820 Hancock, G.; Lam, C. (1999) Toxicity of MKH 3586 Technical to the Green Alga 

Selenastrum capricornutum: Lab Project Number: 109248: M6883501. 

Unpublished study prepared by Bayer Corp. 34 p. 

45121827 Hall, A.; Lam, C. (2000) Toxicity of Desamino MKH 3594 a Metabolite of MKH 

3586, to the Green Alga Selenastrum capricornutum: Lab Project Number: 

108934: 98-B-202. Unpublished study prepared by Bayer Corp. 30 p. 

 

850.4550 Cyanobacteria Toxicity 

 MRID Citation Reference

45121825 Hall, A.; Lam, C. (1999) Toxicity of MKH 3586 Technical to the Bluegreen Alga 

Anabaena flos-aquae: Lab Project Number: 108935: M6883801. Unpublished 

study prepared by Bayer Corp. 37 p. 

850.3020 Honey bee acute contact 

MRID Citation Reference
37 

45121816 Schmitzer, S. (1998) Laboratory Testing for Toxicity (Acute Contact and Oral 

LD(50)) of MKH 3586 on Honey Bees (Apis mellifera L.) (Hymenoptera, 

Apidae): Lab Project Number: 109350. Unpublished study prepared by Institute 

for Biological Analysis and Consulting IBACON GmbH. 28 p. 
38 

Appendix A. Amicarbazone Transformation Products 
39

Appendix B. SIP analysis inputs and results 

 Table 1. Inputs 

 Parameter Value 

 Chemical name amicarbazone 

 Solubility (in water at 25oC; mg/L) 4,600 

 

 Mammalian LD50 (mg/kg-bw) 1087 

 Mammalian test species laboratory rat 

 Body weight (g) of "other" mammalian species 

 

 Mammalian NOAEL (mg/kg-bw) 6.4 

 Mammalian test species laboratory rat 

 Body weight (g) of "other" mammalian species 

 

 Avian LD50 (mg/kg-bw) 1965 

 Avian test species northern bobwhite quail 

 Body weight (g) of "other" avian species 

 Mineau scaling factor 1.15 

 

 Mallard NOAEC (mg/kg-diet) 27.1 

 Bobwhite quail NOAEC (mg/kg-diet) 27.1 

 NOAEC (mg/kg-diet) for other bird species 

 Body weight (g) of other avian species 

 

NOAEC (mg/kg-diet) for 2nd other bird 

species 

 Body weight (g) of 2nd other avian species 

 Table 2. Mammalian Results 

 Parameter Acute Chronic 

 Upper bound exposure (mg/kg-bw) 791.2000 791.2000 

 Adjusted toxicity value (mg/kg-bw) 836.0775 4.9226 

 Ratio of exposure to toxicity 0.9463 160.7272 

 

Conclusion* 

Exposure through drinking 

water alone is a potential 

concern for mammals 

Exposure through drinking 

water alone is a potential 

concern for mammals 

 

 Table 3. Avian Results 

 Parameter Acute Chronic 

 Upper bound exposure (mg/kg-bw) 3726.0000 3726.0000 

 Adjusted toxicity value (mg/kg-bw) 1415.6440 1.3445 

 Ratio of exposure to acute toxicity 2.6320 2771.2895 

 

Conclusion* 

Exposure through drinking 

water alone is a potential 

concern for birds 

Exposure through drinking 

water alone is a potential 

concern for birds 

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, 

when aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through drinking water may 

contribute to a total exposure that has potential for effects to non-target animals. 
40

Appendix C. STIR analysis results 

Input 

Application and Chemical Information 

Enter Chemical Name Amicarbazone 

Enter Chemical Use Corn, Turf, Conifers 

Is the Application a Spray? (enter y or n) y 

If Spray What Type (enter ground or air) ground 

Enter Chemical Molecular Weight (g/mole) 241 

Enter Chemical Vapor Pressure (mmHg) 2.20E-08 

Enter Application Rate (lb a.i./acre) 0.45 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 1965 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 0.178 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 1087 

Enter Lowest Rat Inhalation LC50 (mg/L) 2.242 

Duration of Rat Inhalation Study (hrs) 4 

Enter Rat Weight (kg) 0.35 

 

Output 

Results Avian (0.020 kg ) 

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.85E-04 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.59E-05 

Adjusted Inhalation LD50 2.26E+01 

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.59E-06

Exposure not Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 4.76E-02 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 2.10E-03

Exposure not Likely 

Significant 

 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.85E-04 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.51E-05 

Adjusted Inhalation LD50 1.33E+02 

Ratio of Vapor Dose to Adjusted Inhalation LD50 3.38E-07

Exposure not Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 5.98E-02 

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 4.48E-04

Exposure not Likely 

Significant