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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

OFFICE OF PREVENTION, PESTICIDE

AND TOXIC SUBSTANCES

MEMORANDUM

August 19, 2010

SUBJECT: Acibenzolar-S-methyl Human Health Risk Assessment for Proposed Use of 

Acibenzolar-S-methyl on Turf and Cotton Seed.

PC Code: 061402 DP Barcode: 379425

Decision No.: 422406 Registration No.: 100-RGAG

Petition No.: NA Regulatory Action: Section 3 Registration

Risk Assessment Type: Single Chemical Aggregate Case No.: 7031

TXR No.: NA CAS No.: 135158-54-2

MRID No.: NA 40 CFR: 180.561

FROM: Becky Daiss, Biologist 

James Scott Miller, Environmental Scientist

Bonnie Cropp-Kohlligian, Environmental Scientist

Risk Assessment Branch 4

Health Effects Division (7509P)

THROUGH: Susan V. Hummel, Branch Senior Scientist

Risk Assessment Branch 4, HED (7509P)

TO: Janet Whitehurst, Risk Manager Review

Fungicide Branch

Registration Division (7505P)

This document provides the Health Effects Division’s (HED’s) risk assessment of use of 

acibenzolar-S-methyl on turf and cotton seed. Supporting documents are listed below.

Occupational Exposure Assessment – J.S. Miller, D245704, 8/19/2010

Residue Chemistry Assessment – B. Cropp-Kohlligian, D373132, 4/29/10

Dietary and Drinking Water Exposure Assessment – B. Daiss, D380742, 8/19/10

Drinking Water Exposure Assessment – R. Miller, D380135, 7/9/10
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TABLE OF CONTENTS

 pg.

1.0 EXECUTIVE SUMMARY..................................................................................................4

2.0 INGREDIENT PROFILE ....................................................................................................7

2.1 Registered Products .............................................................................................................7

2.2 Registered and Proposed New Uses.....................................................................................7

2.3 Structure, Nomenclature and Physical/Chemical Properties ...............................................7

3.0 HAZARD CHARACTERIZATION/ASSESSMENT ........................................................9

3.1 Hazard Characterization ......................................................................................................9

3.2 FQPA Hazard Considerations ...........................................................................................10

3.2.1 Developmental Toxicity .......................................................................................10

3.2.2 Reproductive Toxicity ...........................................................................................12

3.2.3 Developmental Neurotoxicity................................................................................13

3.2.4 Pre-and/or Postnatal Toxicity.................................................................................14

3.2.5 Immunotoxicity......................................................................................................14

3.2.6 FQPA Factor..........................................................................................................14

3.3 Toxicity Endpoint Selection ..............................................................................................14

3.3.1 Acute Reference Dose – General Population ........................................................14

3.3.2 Chronic Reference Dose – Females Age 13-49 & Young Children ......................15

3.3.3 Chronic Reference Dose – Adult Males and Females Age 50+.............................16

3.3.4 Incidental Oral Exposure .......................................................................................17

3.3.5 Dermal Absorption.................................................................................................18

3.3.6 Dermal Exposure ...................................................................................................19

3.3.7 Inhalation Exposure ...............................................................................................19

3.3.8 Classification of Carcinogenic Potential................................................................18

3.4 Margins of Exposure..........................................................................................................19

3.5 Recommendation for Aggregate Exposure ........................................................................19

3.6 Summary of Endpoints Selected for Risk Assessment ......................................................20

3.7 Endocrine Disruption.........................................................................................................21

4.0 DIETARY AND DRINKING WATER EXPOSURE ASSESSMENT ............................22

4.1 Residue Chemistry Profile .................................................................................................22

4.1.1 Metabolism in Primary Crops................................................................................22

4.1.2 Residue Analytical Method....................................................................................22

4.1.3 Residues in Crops ..................................................................................................23

4.2 Drinking Water Profile ......................................................................................................23

4.2.1 Environmental Fate and Transport.........................................................................24

4.2.2 Estimated Drinking Water Concentrations............................................................23

4.3 Dietary and Drinking Water Exposure and Risk................................................................24

4.3.1 Acute Dietary and Drinking Water Analysis .........................................................25

4.3.2 Chronic Dietary and Drinking Water Analysis......................................................25
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5.0 RESIDENTIAL EXPOSURE AND RISK ASSESSMENT .............................................26

5.1 Exposure Scenarios ...........................................................................................................26

5.1.1 Handler Exposure Scenarios ...................................................................................26

5.1.2 Post-Application Exposure Scenarios .....................................................................26

5.2 Exposure Data and Assumptions ......................................................................................26

5.2.1 Handler Exposure Scenarios .................................................................................27

5.2.2 Post-Application Exposure Scenarios ..................................................................27

5.3 Residential Exposure and Risk Estimates .........................................................................28

5.3.1 Handler Exposure and Risk ..................................................................................28

5.3.2 Post-Application Exposure and Risk ....................................................................28

6.0 AGGREGATE EXPOSURE AND RISK ASSESSMENT ...............................................29

6.1 Acute and Chronic Aggregate Risk ...................................................................................30

6.2 Short Term Aggregate Risk ..............................................................................................30

7.0 OCCUPATIONAL EXPOSURE AND RISK ...................................................................30

7.1 Exposure Scenarios............................................................................................................30

7.1.1 Handler Exposure Scenarios..................................................................................31

7.1.2 Post Application Exposure Scenarios....................................................................31

7.2 Occupational Exposure Data and Assumptions.................................................................31

7.2.1 Exposure Data........................................................................................................31

7.2.2 Exposure Assumptions ..........................................................................................32

7.3 Occupational Exposure and Risk Estimates .....................................................................33

7.3.1 Handler Exposure and Risk Estimates...................................................................33

7.3.2 Post-Application Exposure and Risk Estimates.....................................................34

8.0 CUMULATIVE RISK .......................................................................................................35

9.0 DATA NEEDS...................................................................................................................36

9.1 Toxicity Data Requirements ..............................................................................................36

APPENDICES

1.0 GUIDELINE TOXICOLOGY DATA SUMMARY..........................................................37

1.1 Guideline Data Requirements................................................................................37

1.2 Toxicity Profiles.....................................................................................................38

2.0 STUDIES REVIEWED FOR ETHICAL CONDUCT ......................................................43

3.0 ADDITIONAL TOXICITY STUDIES..............................................................................44

4.0 REFERENCES FOR TOXICITY STUDIES.....................................................................50

5.0 CHEMICAL NAMES AND STRUCTURES OF METABOLITES.................................53
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1.0 EXECUTIVE SUMMARY

This assessment provides information to support an amended Section 3 registration for 

the use of acibenzolar-S-methyl on cucurbit cotton and turf. This document addresses the 

exposures and risks associated with exposures from currently registered uses and the proposed 

new uses of acibenzolar-S-methyl. 

Use Profile

Acibenzolar-S-methyl is a plant activator. It is a member of the benzothiadiazole class of 

compounds. Acibenzolar-S-methyl is registered to Syngenta Crop Protection, Inc for use on 

leafy vegetables, Brassica leafy vegetables, fruiting vegetables, and tobacco for the control or 

suppression of downy mildew, black rot, white rust, bacterial leaf spot and speck, and blue mold.

Permanent tolerances ranging from 0.1-3.0 ppm are established under §180.561(a). Section 18 

time-limited tolerances are established under §180.561(b) for bulb and green onion (0.05 ppm). 

Acibenzolar-S-methyl acts to protect plants against invading pathogen by inducing a natural 

defense reaction that enhances the plants ability to ward off disease. Applications may be made 

using ground or aerial equipment. The proposed new use on turf grass is the first use of 

acibenzolar-S-methyl products intended for homeowner use and application to residential areas. 

 

Proposed New Uses

Syngenta Crop Protection, Inc. has submitted an application for the registration of two

new products, BionTM 500 FS and Daconil ACTionTM. BionTM 500 FS (EPA Reg. No. 100-

RGAU) is a flowable concentrate formulation containing 42.0% acibenzolar-S-methyl 

(equivalent to 4.17 lb ai/gal). It is proposed for use in commercial seed treatment operations for 

protection against certain early season seed and seed –borne nematodes in cotton. Daconil 

ACTionTM (EPA Reg. No. 100-RGAG) is also a flowable formulations containing 11% 

acibenzolar-S-methyl). It is proposed for use on sod farms, golf courses, collegiate athletic 

fields, and lawns around commercial and industrial buildings to control turf diseases. The 

Daconil ACTionTM product also contains 54% chlorthanalonil, however, only acibenzolar-Smethyl exposures are evaluated for this assessment. 

Hazard Identification

The toxicology database for acibenzolar-S-methyl is adequate for evaluating and 

characterizing toxicity and selecting endpoints for purposes of this risk assessment. 

Acibenzolar-S-methyl showed no significant toxicity in a battery of acute toxicity tests 

(Toxicity Category III or IV in all tests) but showed considerable skin-sensitivity. The end-use 

product (ActigardTM 50Wg) displayed no significant acute toxicity and no dermal sensitizing 

potential. In subchronic and chronic oral studies in rats, dogs and mice, signs of mild 

regenerative hemolytic anemia were consistently observed in all three species. Additional toxic 

effects observed in these studies included decreases in body weight, body weight gain and/or 

food consumption. No other significant treatment-related effects of toxicological concern were 
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observed in these subchronic and chronic oral studies. No neurotoxic effects were seen at the 

highest dose tested in a subchronic neurotoxicity study in rats. In a 28 day dermal toxicity study

in rats no systemic or dermal effects were seen at the limit dose. 

In a developmental toxicity and developmental neurotoxicity studies in rats, treatment 

related effects were observed in fetuses at levels that were not toxic to the parent indicating 

increased sensitivity of rat fetuses compared to adults. Increased sensitivity was not observed in 

a developmental toxicity study in rabbits, or in 1- and 2-generation reproduction studies in rats. 

In a 28 day dermal developmental toxicity study in rats, no maternal or developmental toxicity

was observed at dose levels up to 500 mg/kg/day, the highest dose level tested. 

Acibenzolar-S-methyl was classified by HED’s Hazard Identification Assessment Review 

Committee (HIARC) as a “not likely” human carcinogen based on negative carcinogenicity

studies in male and female rats and mice and negative results in an acceptable battery of 

genotoxicity studies. 

An immunotoxicity study is required as part of new 40 CFR Part 158 the data 

requirements for registration of a pesticide. A battery of mutagenicity studies performed on 

technical-grade acibenzolar-S-methyl prepared by the thiazole production process and an Ames 

assay using the technical-grade acibenzolar-S-methyl prepared by the thiazole production process 

are required.

Dose Response Assessment

Toxicological endpoints were selected for dietary/drinking water, occupational and 

residential exposure scenarios. Acute and chronic reference doses (RfDs) were selected for 

assessment of food and drinking water exposures. An acute RfD for the general population was 

not selected because no effect attributable to a single day oral exposure was observed in animal 

studies. Acute and chronic RfD’s for females 13-49 were selected from a developmental 

neurotoxicity toxicity study in rats. A chronic RfD for the general population was selected from 

a chronic feeding study in dogs with chronic studies in other species co-critical. Short and 

intermediate-term occupational exposures via the dermal and inhalation routes may occur based 

on the use pattern and label directions. Toxicological endpoints for inhalation, dermal, and 

incidental oral exposures were selected from the developmental neurotoxicity study in rats. An

uncertainty factor of 100X was applied to endpoints selected for all exposure routes (10x for 

interspecies extrapolation, 10x for intraspecies variation). 

Exposure/Risk Assessment and Risk Characterization

Risk assessments were conducted for dietary (food and water), occupational, and 

residential exposure pathways based on registered uses and requests for new uses of acibenzolarS-methyl on cucurbit vegetable and bulb onions. Although both of these products are designated 

for occupational/commercial use only, labels stipulate use on golf courses and on lawns around 

commercial buildings which may include apartment complexes. Therefore residential golfer and 

post application exposure scenarios were assessed. Workers exposures were assessed for handler 
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and post-application activities. Residential exposures were assessed for adult handlers and adult 

and child post-application activities. Refined acute and screening level chronic dietary and

drinking water risk assessments for acibenzolar-S-methyl conclude that dietary and drinking 

water exposure estimates are below HED’s level of concern the general population and all 

population subgroups. Occupational and residential exposure and risk estimates indicate that 

worker and residential handler and post-application exposures are not of concern at the 

maximum allowable application rates for the proposed new uses. 

Use of Human Studies

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

were intentionally exposed to a pesticide or other chemical. These studies, listed in Appendix 

2.0, have been determined to require a review of their ethical conduct. Some of these studies are 

also subject to review by the Human Studies Review Board. All of the studies used have 

received the appropriate review.

Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered 

in this human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal 

Actions to Address Environmental Justice in Minority Populations and Low-Income 

Populations," http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf).

As a part of every pesticide risk assessment, OPP considers a large variety of consumer 

subgroups according to well-established procedures. In line with OPP policy, HED estimates 

risks to population subgroups from pesticide exposures that are based on patterns of that 

subgroup’s food and water consumption, and activities in and around the home that involve 

pesticide use in a residential setting. Whenever appropriate, non-dietary exposures based on 

home use of pesticide products and associated risks for adult applicators and for toddlers, youths, 

and adults entering or playing on treated areas postapplication are evaluated. Further 

considerations are currently in development, as OPP has committed resources and expertise to 

the development of specialized software and models that consider exposure to bystanders and 

farm workers as well as lifestyle and traditional dietary patterns among specific subgroups. 

Food Use Recommendation

Based on the results of the metabolism (radiotracer) study, conducted at the maximum 

proposed use rate, which demonstrated that the total transferable residue (TRR) levels in/on all 

raw agricultural commodities of cotton were < 5 ppb, HED concludes that the proposed use of 

BionTM 500FS as a cottonseed treatment meets EPA’s criteria for nonfood/nonfeed use 

classification, as defined in EPA’s Chemistry Science Advisory Council’s (ChemSAC’s) 28 

October 1999 memorandum, Classification of Seed Treatments as Food or Nonfood Uses. No 

additional data on residues of acibenzolar-S-methyl in/on cotton grown from treated seed are 

needed to support the proposed use. 
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2.0 INGREDIENT PROFILE 

2.1 Registered Products

There are currently 7 active acibenzolar-S-methyl registrations including two Section 3 

registrations and five special local needs (SLNs) or 24(c) registrations. 

Table 1. Summary Report of Supported Registered Acibenzolar-S-methyl Products

Reg # Name Company Name %AI

100-921 Acibenzolar-S-Methyl Technical

Syngenta Crop Protection, Inc.

99

100-922 Actigard 50WG 50

FL030003 Actigard 50 WG Plant Activator 50

GA020005 Actigard 50 WG Plant Activator 50

NC020007 Actigard 50 WG Plant Activator 50

SC030004 Actigard 50 WG Plant Activator 50

VA030002 Actigard 50 WG Plant Activator 50

2.2 Registered and Proposed New Uses 

Acibenzolar-S-methyl is a “plant activator” that protects the plant against invading 

pathogens by stimulating the plant’s natural defense mechanisms. The single registered 

formulation, Actigard® (EPA Reg. No. 100-922), is a water-dispersible granule (WG) containing 

50% acibenzolar-S-methyl. Syngenta is requesting registration of two new products. BionTM 

500 FS (EPA Reg. No. 100-RGAU) and Daconil ACTionTM (EPA Reg. No. 100-RGAG). 

BionTM 500 FS is a flowable concentrate formulation containing 42.0% acibenzolar-S-methyl 

(equivalent to 4.17 lb ai/gal). It is proposed for use in commercial seed treatment operations for 

protection against certain early season seed and seed-borne nematodes in cotton. Application 

rates range from 0.0003 mg ai to 0.0009 mg a.i per seed based on 5,000 seeds per pound. 

Daconil ACTionTM is a flowable formulations containing 11% acibenzolar-S-methyl (and 54% 

chlorthalonil) proposed for use on sod farms, golf courses, collegiate athletic fields, and lawns 

around commercial and industrial buildings to control turf diseases. Application rates range from 

4.0 to 5.4 fl oz of product per 1,000 sq. feet with a maximum single application rate of 0.022 lbs 

ai/Acre. 

Table 2. Maximum Application Rates for Acibenzolar-S-methyl Existing and Proposed Uses

Application Site Max % AI Maximum AR Reg No.

Leafy vegetables, Brassica leafy vegetables, Fruiting 

Vegetables, Tobacco and Bulb Onion subgroup 3-07A 50

0.03 lb/ai A

100-922

Cucurbit vegetable crop group 9 0.06 lb/ai A

Turf Use 11 0.022 lb/ai A 100-RGAG

Cotton Seed 24 0.0009 mg/ai Seed
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2.3 Structure, Nomenclature, and Physical/Chemical Properties 

The nomenclature and physicochemical properties of acibenzolar-S-methyl are provided 

in Tables 3 and 4.

Table 3. Acibenzolar-S-Methyl Nomenclature.

Chemical structure

N

N

S

O S

CH3

Common name acibenzolar-S-methyl

Company experimental name CGA-245704

IUPAC name benzo[1,2,3]thiadiazole-7-carbothioic acid-S-methyl ester

CAS name S-methyl, 1,2,3-bensothiadiazole-7-carbothioate

CAS registry number 135158-54-2

End-use product (EP) Actigard® 50 WG (EPA Reg. No. 100-922)

Structure of metabolite 

CGA-210007

N

N

S

COOH

1,2,3-benzothiadiazole-7-carboxylic acid

Table 4. Physicochemical Properties of Acibenzolar-S-Methyl.

Parameter Value Reference

Melting point/range 133 oC DP# 250963, 2/10/99, H. Podall

pH 7.9 (1% solution in water) at 25 oC

Density 1.54 g/cc at 22 oC (bulk density)

Water solubility 0.0077 g/L

Solvent solubility Methanol 4.2 g/L

Acetone 28 g/L

Toluene 36 g/L

n-Octanol 5.4 g/L

n-Hexane 1.3 g/L

Ethyl acetate 25 g/L

Dichloromethane 160 g/L 

European Commission, 

6506/VI/99-final, 5/21/02

Vapor pressure 3.6 x 10-6 Torr at 25 oC DP# 250963, 2/10/99, H. Podall

Dissociation constant, pKa No dissociation constant in an

accessible pH range (1.0 - 9.0)

European Commission, 

6506/VI/99-final, 5/21/02

Octanol/water partition coefficient, 

Log(KOW)

Log (POW) 3.1 at 25 oC DP# 250963, 2/10/99, H. Podall

UV/visible absorption spectrum 253 nm ε : 14.7 103l mol-1cm-1

288 nm ε : 5.4 103

324 nm ε : 7.2 103

European Commission, 

6506/VI/99-final, 5/21/02
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3.0 HAZARD CHARACTERIZATION/ASSESSMENT

3.1 Hazard Characterization

The toxicology database for acibenzolar-S-methyl is adequate for evaluating and 

characterizing acibenzolar-S-methyl toxicity and selecting endpoints for purposes of this risk 

assessment. An immunotoxicity study is required as part of new 40 CFR Part 158 data 

requirements for registration of a pesticide. An Ames assay and a battery of other mutagenicity

studies performed on technical-grade acibenzolar-S-methyl prepared by the thiazole production 

process are required.

Acibenzolar-S-methyl showed no significant toxicity in a battery of acute toxicity tests 

(Toxicity Category III or IV in all tests). Considerable skin sensitizing (contact allergenic) 

potential was demonstrated in a dermal sensitization study in guinea pigs. The formulated enduse product (ActigardTM 50 WG) also demonstrated no significant acute toxicity; additionally, 

the end-use product did not show dermal sensitization in guinea pigs.

In subchronic and chronic oral studies in rats, dogs and mice, signs of mild regenerative 

hemolytic anemia were consistently observed in all three species. These signs frequently

included decreased erythrocyte counts, decreased hemoglobin, decreased hematocrit, increased 

reticulocyte counts, increased hemosiderosis in the spleen, liver and/or bone marrow, 

extramedullary hematopoiesis in the spleen, and increased spleen weights in both males and 

females. A compensatory response (increased erythrocyte production) regularly followed the 

initial anemia. Additional toxic effects observed in these same studies included decreases in 

body weight, body weight gain and/or food consumption. No other significant treatment-related 

effects of toxicological concern were observed in these subchronic and chronic oral studies. In a 

28-day dermal study in rats, no systemic or dermal effects were observed at dose levels up to 

1000 mg/kg/day, the limit dose. No neurological effects were observed at any dose in a 

subchronic neurotoxicity study in rats.

Treatment-related developmental malformations, anomalies and variations were observed 

in a developmental toxicity study in rats at or below the no observable adverse effect level 

(NOAEL) for maternal toxicity. At the highest dose tested in this study (400 mg/kg/day), both 

maternal toxicity (hemorrhagic perineal discharge) and considerable developmental toxicity

(including total litter resorptions, fetal malformations, anomalies and variations) were observed. 

The fetal malformations noted at this dose included treatment-related effects on nervous system 

tissues (hydrocephaly, craniorachisis and anophthalmia/ microphthalmia). At the next lower 

dose tested (200 mg/kg/day), treatment-related visceral malformations and skeletal variations 

were demonstrated in the absence of significant maternal toxicity. A similar increased sensitivity

of fetuses or pups (as compared to adults) was not observed in a developmental toxicity study in 

rabbits or in 2-generation and 1-generation (range-finding) studies in rats. In a dermal 

developmental toxicity study in rats, no maternal or developmental toxicity was observed at dose 

levels up to 500 mg/kg/day, the highest dose tested. 

In a metabolism study in rats, acibenzolar-S-methyl was rapidly and nearly completely
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absorbed and excreted in less than 48 hours. The major route of excretion was urine (88-95%). 

The major metabolite in urine was the carboxylic acid derivative of parent (79-92%). 

In a battery of mutagenicity studies, results were negative in all studies except in an in 

vitro chromosome aberration study in Chinese hamster ovary (CHO) cells, in which there was 

evidence of a clastogenic response in the absence of S-9 activation. This finding, however, can 

only be considered to be suggestive evidence of a possible aneuploidy effect since negative 

results were observed in an in vivo mouse micronucleus assay. In a S. typhimurium reverse gene 

mutation assay performed on a structural isomer (CGA- 362020) of acibenzolar-S-methyl, 

positive results were observed in strain TA1537 in the absence of S-9 activation. This isomer is 

found at low levels (< 0.1%) in some batches of technical-grade acibenzolar-S-methyl 

manufactured by a new “thiazole process.” Therefore, an Ames assay and a battery of 

mutagenicity studies performed on technical-grade acibenzolar-S-methyl prepared by that process

are required.

In a 2-year chronic toxicity/carcinogenicity study in rats and an 18-month carcinogenicity

study in mice, acibenzolar-S-methyl was negative for carcinogenicity when administered at dose 

levels adequate for the testing of carcinogenic potential. 

The complete toxicity profile for acibenzolar-S-methyl is provided in Appendix 1.2, 

Tables 2 and 3. 

3.2 FQPA Hazard Considerations

The toxicity database for acibenzolar-S-methyl is sufficient for a full hazard evaluation 

and is considered adequate to evaluate risks to infants and children. Acceptable developmental 

toxicity studies in the rat and rabbit, acceptable multi- and single generation reproduction studies

in the rat, and an acceptable developmental neurotoxicity study in the rat are available. An 

acceptable subchronic neurotoxicity study in the rat is also available in the database. An acute 

neurotoxicity study is not available but not required at this time due to the availability of the 

subchronic neurotoxicity study in which no neurological effects were observed at any dose. 

3.2.1 Developmental Toxicity 

3.2.1.1 Rat Developmental Study 

Study 1 

In a developmental toxicity study (MRID 44014236), 24 pregnant Tif: RAI f (SpragueDawley derived) rats per group were administered acibenzolar-S-methyl by gavage in 0.5% 

(W/W) aqueous sodium carboxymethyl-cellulose (vehicle) at daily doses of 0, 10, 50, 200, or 400 

mg/kg/day on gestation days (GD) 6-15, inclusive. Controls were treated only with 0.5% sodium 

carboxymethyl-cellulose. On GD 21, all dams were sacrificed and subjected to gross necropsy

and fetuses were examined for external, visceral, and skeletal malformations and variations. All 

animals survived to scheduled sacrifice. 
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Treatment-related hemorrhagic perineal discharge was observed in the 400 mg/kg/day

group. No other treatment-related clinical signs of toxicity were observed in any animal. 

Interpretations of changes in body weight, body weight gain and food consumption for the 400 

mg/kg/day animals were severely compromised because the data were based on only 6 animals (3 

of which had 50% resorptions compared to the number of implantation sites). The maternal 

toxicity LOAEL is 400 mg/kg/day based on clinical signs of hemorrhagic perineal discharge. The 

maternal toxicity NOAEL is 200 mg/kg/day. 

There were no differences between the control group and any treatment group for number 

of animals pregnant, mean number of corpora lutea per dam, or mean number of implantation 

sites per dam. At 400 mg/kg/day (highest dose tested), treatment-related complete litter 

resorptions, increased postimplantation loss, decreased mean live fetuses/litter, decreased mean 

fetal body weights, and several developmental malformations, anomalies, and skeletal variations 

were observed. At 200 mg/kg/day, treatment-related developmental malformations and skeletal 

variations were also observed. The developmental toxicity LOAEL is 200 mg/kg/day based on 

developmental malformations, anomalies, and skeletal variations. The developmental toxicity

NOAEL is 50 mg/kg/day. 

Study 2

In a developmental toxicity study (MRID 45089701), acibenzolar-S-methyl in aqueous 

0.5% carboxymethylcellulose was administered via daily oral gavage in a dose volume of 10 

mL/kg to 22 presumed pregnant Sprague-Dawley rats at doses of 0, 10, 75, 150, or 350 

mg/kg/day from gestation days (GD) 6-15. On GD 20, all dams were euthanized; each dam’s 

uterus was removed via cesarean section and its contents examined. Fetuses were examined for 

external, visceral, and skeletal malformations and variations.

All dams survived until scheduled termination, and there were no clinical signs of toxicity

during the study or gross lesions at necropsy. Furthermore, there were no effects of treatment on 

maternal body weights, body weight gains, or food consumption. A maternal LOAEL was not 

observed. The maternal NOAEL is 350 mg/kg/day.

There were no abortions, premature deliveries, or complete litter resorptions. There were 

no effects of treatment on the numbers of litters, live fetuses, early resorptions, or late 

resorptions, resulting in post-implantation loss values in the treated groups that were comparable 

to controls. There were no treatment-related effects on placental weights, fetal body weights, or 

skeletal ossification. The number of fetuses with skeletal variations was significantly increased 

(p<0.05) at 350 mg/kg/day (60) compared to controls (18). This increase was accounted for by

increased (p<0.05) incidences of fetuses with rudimentary lumbar ribs (31 fetuses compared to 9 

controls) and long lumbar ribs (24 fetuses vs 0 controls). There were no other treatment-related 

external, visceral, or skeletal variations. There were no treatment-related external, visceral, or 

skeletal malformations. The developmental LOAEL is 350 mg/kg/day based on increased 

incidences of rudimentary and long lumbar ribs. The developmental NOAEL is 150 mg/kg/day.
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3.2.1.2 Rabbit Developmental Study 

In a developmental toxicity study (MRID 44014237), 17 pregnant Russian Chbb:HM 

rabbits per group were administered acibenzolar-S-methyl by gavage in an aqueous solution of 

carboxymethylcellulose (0.5% w/w) at doses of 0 (vehicle), 10, 50, 300, and 600 mg/kg/day on 

gestation days (GD) 7-19, inclusive. On GD 29, all surviving does were sacrificed and all fetuses 

were weighed and examined for external malformations/variations and visceral abnormalities/

variations. 

Three 600 mg/kg/day does were found dead and three more were sacrificed moribund 

during GD 13-28. All exhibited moderate to extreme body weight loss and reduced food 

consumption, two had perineal bleeding, two had diarrhea, and one had reduced motor activity. 

At 300 mg/kg/day, one doe was found dead on GD 18. This animal showed body weight loss 

and reduced food consumption prior to death. Gross necropsy findings in animals that died 

intercurrently included stomach hemorrhage in three of the 600 mg/kg/day does and in the 300 

mg/kg/day doe. No mortality or treatment-related clinical signs of toxicity were observed for the 

10 and 50 mg/kg/day treatment groups. There were no significant differences in maternal body

weights, body weight changes, and food consumption in the surviving animals from the treated 

and control groups at any time during gestation. Therefore, the maternal toxicity LOAEL is 300 

mg/kg/day based on mortality, clinical signs of toxicity, and substantially decreased body weights 

and food consumption. The maternal toxicity NOAEL is 50 mg/kg/day.

No treatment-related effects were observed for gravid uterine weights, number of 

fetuses/litter, pre- and postimplantation loss, numbers of corpora lutea/doe, number of 

implantations/doe, resorptions/doe, fetal body weights, or fetal sex ratios. At 600 mg/kg/day

there was a slight but significant increase in asymmetrically shaped caudal vertebral centers (3 

fetuses in 3 litters compared to 0 fetuses or affected litters in the control group). No statistically

significant differences in the incidence rates of any external or visceral malformations/anomalies/ 

variations were observed in the treated litters as compared to controls. Therefore, the 

developmental toxicity LOAEL is 600 mg/kg/day based on a marginal increase in vertebral 

anomalies. The developmental NOAEL is 300 mg/kg/day.

3.2.2 Reproductive Toxicity 

In a 2-generation reproduction toxicity study, acibenzolar-S-methyl was administered to 

groups of 30 male and 30 female Tif: RAT f(SPF), hybrids of RII/1 x RII/2 (Sprague-Dawley

derived) rats at dietary concentrations of 0, 20, 200, 2000, or 4000 ppm for two generations 

(MRID 44014241). Two litters were produced in the first generation and one litter was produced 

in the second generation. F1 adults were chosen from the F1a pups and weaned onto the same 

diet as their parents. Animals were given test or control diet for 10 weeks before mating within 

the same dose group. All animals were continuously exposed to test material either in the diet or 

during gestation and lactation until sacrifice.

No treatment-related clinical signs of toxicity were observed in males or females of either 

generation at any time during the study. Lower body weights and food consumption for high 

dose dams was observed during lactation. No dose- or treatment-related effects on body weights, 
Page 13 of 53

body weight gains, or food consumption were observed for the F1 males or females in the 20, 

200, or 2000 ppm groups. Absolute body weights were significantly reduced in high-dose F1 

males throughout the study and in high-dose F1 females through study day 57. No significant 

differences in body weights and food consumption for the F0 and F1 dams were observed during 

gestation. Absolute spleen weights were significantly increased in both the 4000 and 2000 ppm 

F0 and F1 animals. Relative spleen weights were significantly increased in the 2000 and 4000 

ppm F0 and F1 males and females. High-dose F0 males also had significantly increased absolute 

and relative kidney weights. A dose-related increase in the severity of splenic hemosiderosis was 

observed in F0 and F1 males and females. This finding was associated with an increase in the 

incidence of splenic congestion in the high-dose groups. The LOAEL for parental toxicity is 

2000 ppm based on increased spleen weights and hemosiderosis of the spleen in the F0 and F1 

males and females. The parental toxicity NOAEL is 200 ppm. Mating, fertility, gestation, and 

parturition indices, mean precoital interval, and mean gestation length were similar between the 

treated and control groups of both generations. Mean litter size, live births, and pup survival 

were also similar between the treated and control groups for both generations. Therefore, the 

NOAEL for reproductive toxicity is 4000 ppm (highest dose tested). A LOAEL for reproductive 

toxicity was not observed (>4000 ppm).

No treatment-related clinical signs of toxicity were observed in the F1a, F1b, or F2 pups 

during lactation. Body weights of the 4000 ppm group F1a, F1b, and F2 pups were significantly

less than the controls on lactation days 4, 7, 14, and 21. Body weights of the F1a, F1b, and F2 

pups in the 2000 ppm group were significantly less than their respective controls on lactation day

21. Body weight gains by the high-dose F1a and F2 pups throughout lactation and by the highdose F1b pups beginning on lactation day 4 were significantly less than the controls. The

LOAEL for developmental toxicity is 2000 ppm based on reduced pup body weight gains and 

lower pup body weights during lactation. The developmental toxicity NOAEL is 200 ppm.

3.2.3 Developmental Neurotoxicity Study 

In a developmental neurotoxicity study (MRID 46046401) acibenzolar-S-methyl was 

administered in the diet to pregnant Wistar rats (30/dose) from gestation day (GD) 7 to lactation 

day (LD) 22 at nominal doses of 0, 100, 1000, or 4000 ppm (equivalent to 0/0, 8.2/15.5, 

82.0/153.6, and 326.2/607.8 mg/kg/day [gestation/lactation]). Dams were allowed to deliver 

naturally and were killed on LD 29. On postnatal day (PND) 5, litters were standardized to 8 

pups/litter; the remaining offspring and dams were sacrificed and discarded without further 

examinations. Subsequently, 1 pup/litter/group was allocated to subsets for FOB, motor activity, 

acoustic startle response, learning and memory evaluation, and neuropathological examination. 

A maternal LOAEL was not observed. The maternal NOAEL is 4000 ppm (326.2 mg/kg/day).

In the offspring, no treatment-related effects were seen on survival, clinical signs, FOB, 

developmental land marks, brain weights or neuropathology. No conclusions can be drawn on 

the effects of the compound on motor activity due the lack of consistency in the observations. At 

the high dose, treatment-related effects were decreased body weights and increased auditory

startle response. No differences from controls were observed in any morphometric parameter in 

the treated animals on PND 12, except for increased length from midline in the hippocampus of 
Page 14 of 53

the 4000 ppm females. The following significant differences in various morphometric 

measurements were noted on PND 63: (i) decreased dorsal cortex 1 thickness at 100 ppm in 

males; (ii) decreased dorsal cortex 2 thickness at 100 ppm in males; (iii) decreased thickness of 

the molecular layer of the cerebellum at the preculminate fissure in the 4000 ppm males; (iv) 

decreased thickness of the molecular layer of the cerebellum at the prepyramidal fissure in the 

1000 ppm males; and (v) increased thickness of the corpus callosum in the 4000 ppm females. 

The biological significance of the reduction in the dorsal cortex, which is not dose-dependent, is 

unclear. The offspring LOAEL is 100 ppm (82 mg/kg/day) based on changes in brain

morphometrics in the cerebellum. The offspring NOAEL is (8.2 mg/kg/day).

3.2.4 Pre-and/or Postnatal Toxicity

The toxicology database for acibenzolar-S-methyl is sufficient for FQPA assessment. In 

the rat developmental toxicity study treatment related visceral malformations and skeletal 

variations were observed in fetuses at 200 mg/kg/day, the NOAEL for maternal toxicity. In the 

developmental neurotoxicity study, offspring toxicity was observed at 82 mg/kg/day while no 

maternal toxicity was observed at 326 mg/kg/day, the highest dose tested. Additional 

developmental toxicity studies in rats and rabbits and reproduction studies in rats provided no 

indication of increased susceptibility of rat or rabbit fetuses or neonates compared to adult 

animals. Based on the results of developmental toxicity and developmental neurotoxicity studies 

in rats there is concern for increased qualitative and/or quantitative susceptibility following in 

utero exposure to acibenzolar-S-methyl. There are no residual uncertainties with regard to preand/or postnatal toxicity. 

3.2.5 Immunotoxicity

There are no indications in the available studies that organs associated with immune 

function, such as the thymus and spleen, are affected by acibenzolar-S-methyl. While effects on 

the spleen were observed in association with hematologic effects, these were considered to 

secondary to the primary effects on blood hematology. Effects on the thymus were seen in only

one study in one animal at a high dose (400 mg/kg/day). An immunotoxicity study is required. 

This is a new data requirement under 40 CFR Part 158 as a part of the data requirements for 

registration of a pesticide (food and non-food uses).

3.2.6 FQPA Factor

The HED Toxicology Science Advisory Committee (ToxSAC) recommended that the 

10X FQPA safety factor be reduced to 1X since endpoints protective of sensitive populations are 

being used in the risk assessment. 

3.3 Toxicity Endpoint Selection

3.3.1 Acute Reference Dose (aRfD) - General Population

Selected Study: Developmental Neurotoxicity in Rats (MRID 46046401). 
Page 15 of 53

See Section 3.2.3

Dose and Endpoint for Establishing an aRfD: 8.2 mg/kg/day based on an offspring 

NOAEL of 8.2 mg/kg/day and an offspring LOAEL of 82 mg/kg/day based on changes in brain 

morphometrics in the cerebellum. 

Uncertainty Factor (UF): 100 – 10x for interspecies extrapolation and 10x for intraspecies 

variation.

Comments about Study/Endpoint: The developmental neurological effects of concern are 

presumed to occur after a single exposure and are relevant to females aged 13-50 years old since 

they occur in utero and to young children based on post-natal effects. 

[Note: In the previous risk assessment (D361893, 3/3/09) only the subpopulation females 

13-50 years old was assessed for acute dietary exposure based on in utero effects. However, 

based on a reevaluation of the DNT study regarding the potential for post-natal toxicity, the acute 

dietary analysis has been expanded to include children for this assessment.]

 

3.3.2 Chronic Reference Dose (cRfD) - Females age 13-49 and Young Children

Selected Study: Developmental Neurotoxicity in Rats (MRID 46046401). 

See Section 3.2.3

Dose and Endpoint for Establishing a cRfD: 8.2 mg/kg/day based on an offspring 

NOAEL of 8.2 mg/kg/day and an offspring LOAEL of 82 mg/kg/day based on changes in brain 

morphometrics in the cerebellum. 

Uncertainty Factor (UF): 100 – 10x for interspecies extrapolation and 10x for intraspecies 

variation.

Comments about Study/Endpoint: The effects observed in this study can occur after 

single or multiple doses. Selection of a chronic endpoint from this study ensures that the chronic 

exposure assessment is protective of females of reproductive age and their offspring.

[Note: In the previous risk assessment (D361893, 3/3/09) only the subpopulation females 

13-50 years old was assessed for chronic dietary exposure based on in utero effects observed in 

the DNT study. However, based on a reevaluation of the DNT study regarding the potential for 

post-natal toxicity, the chronic dietary analysis the chronic dietary exposure analysis has been 

revised to include an assessment of dietary risks to children using the NOAEL from the DNT 

study.]

 Acute RfD = 8.2 mg/kg (NOAEL) = 0.0.082 mg/kg/day

 (General Population) 100 (UF)
Page 16 of 53

3.3.3 Chronic Reference Dose (RfD) – Adult Males and Females 50+ years

Selected Studies: Co-critical studies Chronic Feeding Study in Dogs (MRID 44014234); 

Oncogenicity Study Mouse (MRID 44014235); Chronic/Oncogenicity Study Rat (MRID 

44014243); Reproductive Study Rat (44014241)

Chronic Dog Study - In a chronic oral toxicity study acibenzolar-S-methyl was 

administered to 4 beagle dogs per sex per dose level in gelatin capsules at levels of 0, 5, 25, or 

200 mg/kg/day for 52 weeks. No biologically significant toxic effects were observed in either 

males or females receiving 25 mg/kg/day or less of the test material. At 200 mg/kg/day, there was

an indication of hemolytic anemia in dogs of both sexes i.e., effects consistent with prior or 

current hemolytic anemia including hematological effects, hemosiderosis of the liver and spleen, 

extraniedullary hematopoiesis in the spleen, and increases in liver weight. Significant treatmentrelated changes were found in clinical chemistry in the dogs fed the test, substance at 200 

mg/kg/day, (increase in triglycerides in both sexes, increase of cholesterol in females at week 13, 

decrease in total protein in males at weeks 26 and 52, and decrease in albumin in both sexes at 

week 13. These clinical chemistry changes are suggestive of possible nutritional deficiencies. 

The LOAEL is 200 mg/kg/day in both sexes based on effects consistent with prior or current 

hemolytic anemia. The NOAEL is 25 mg/kg/day. 

Oncogenicity Mouse Study - In an oncogenicity study acibenzolar-S-methyl was 

administered in the diet to groups of 60 male and 60 female Tif:MAGf (SPF) mice at 

concentrations of 0, 10, 100, 2000, or 6000 ppm (1.14, 11.11, 237, and 698 mg/kg/day for males 

and 1.14, 10.8, 234, and 696 mg/kg/day for females) for 18 months. Ten mice per group were 

reserved for measurements of hematology parameters after 12 and 18 months of treatment. 

Treatment did not result in a significant decrease in survival. The overall food efficiency was 

decreased in females by 22% at 6000 ppm. The red blood cell count, hemoglobin, and 

hematocrit at 53 and 79 weeks were decreased in females at 2000 ppm and 6000 ppm. Mean 

corpuscular volume was decreased in high dose males at 79 weeks. Mean corpuscular 

hemoglobin concentration distribution increased at 6000 ppm. Reticulocyte counts in high-dose 

females was significantly increased. The hematology data are consistent with hemolytic anemia 

especially in females at 2000 and 6000 ppm. Macroscopic and microscopic findings consistent 

with a mild hemolytic anemia in both sexes included increased incidences of enlarged spleen, 

increased incidences of hemosiderosis in liver, spleen, and bone marrow. Incidence of 

extramedullary hematopoiesis in the spleen and pancreatic exocrine hyperplasia was increased in 

males at 2000 and 6000 ppm. Incidences of alveolar foam cells in the lungs were increased at 

6000 ppm in both sexes. The LOAEL is 2000 ppm (237/234 mg/kg/day males/females), based 

on mild hemolytic anemia and related microscopic changes (hemosiderosis) in the spleen, liver, 

and bone marrow and extramedullary hematopoiesis in the spleen. The NOAEL was 100 ppm 

(11.1 mg/kg/day males; 10.8 mg/kg/day females).

 Chronic RfD = (NOAEL) 8.2 mg/kg = 0.082

 (Females 13-49/Young Children) (UF) 100
Page 17 of 53

Chronic/Oncogenicity Rat Study - In a chronic toxicity/oncogenicity study, acibenzolarS-methyl was administered in the diet to groups of 80 male and 80 female (Tif:RAIf (SPF)) 

Sprague-Dawley derived rats at concentrations of 0, 20, 200, 2500, or 7500 ppm (0, 0.77, 7.77, 

96.9, and 312 mg/kg/day male and 0, 0.90, 9.08, 111, and 388 mg/kg/day female). Ten animals 

per sex per dose were sacrificed at 52 weeks for interim evaluation; the remaining animals were 

used for hematologic and clinical chemistry evaluation (20 per sex per group) and evaluation of 

carcinogenic potential (50 animals per sex per group). No treatment-related effects were 

observed at 20, 200 or 2500 ppm for any parameter. Treatment related effects on body weight, 

weight gain, food consumption, and food efficiency were observed in both sexes at 7500 ppm. 

Other treatment-related effects at 7500 ppm included a slight hemolytic anemia in both sexes as 

evidenced by decreases in erythrocyte count, increased mean corpuscular volume, elevated 

reticulocyte counts, increased serum bilirubin, increased severity of hemosiderin deposition in 

the spleen, and increased incidence of hemosiderin deposition in Kupifer cells of the liver. 

Hemosiderin deposition in the spleen was accompanied by a statistically significant increase in 

spleen weight. There was also a statistically significant increase in the incidence of foam cells in 

the lungs of females fed the 7500-ppm diet. The LOAEL was 7500 ppm (312/388 mg/kg/day

males/females) based on decreased body weights, body weight gain and food efficiency, mild 

hemolytic anemia, and increased incidence of alveolar foam cells (females only). The NOAEL 

was 2500 ppm (96.9 mg/kg/day males and 111 mg/kg/day females). 

Reproductive Study in Rats - See Section 3.2.2

Dose and Endpoint for Establishing cRfD: 25 mg/kg/day based on a NOAEL of 25 

mg/kg/day from the chronic dog study and a LOAEL of 105 mg/kg/day from the rat reproduction 

study based on hemolytic anemia with compensatory response. 

Uncertainty Factor(s): 100 – 10x for interspecies extrapolation and 10x for intraspecies 

variation.

Comments about Study/Endpoint/Uncertainty Factor: The NOAEL of 25 mg/kg/day, 

taken from the chronic dog study, is based on the totality of the database with a LOAEL of 105 

mg/kg/day (the lowest LOAEL is from the reproduction study) based on hemolytic anemia with 

compensatory response. The NOAEL and LOAEL recommended for use in the risk assessment 

come from different studies conducted in different species. Typically, a combination of 

NOAELs/LOAELs from studies conducted in different species is not recommended. However, 

in the case of acibenzolar-S-methyl the same endpoint (hemolytic anemia) is observed across 

species at a relatively close range of LOAELs (105-312 mg/kg/day). Therefore, the ToxSAC

concluded that, in this instance, it would be appropriate to base the point of departure for the risk 

assessment on the NOAEL from the dog chronic toxicity study using the LOAEL from the 

reproduction study in rats for the basis of the endpoint (hemolytic anemia).

 Chronic RfD = 25 mg/kg/day (NOAEL) = 0.25 mg/kg/day

 (Adult Male) 100 (UF)
Page 18 of 53

3.3.4 Incidental Oral Exposure (Short- and Intermediate-Term)

Selected Study: Developmental Neurotoxicity in Rats (MRID 44014236). 

See Section 3.2.3

Dose and Endpoint: 8.2 mg/kg/day based on an offspring NOAEL of 8.2 mg/kg/day and 

an offspring LOAEL of 82 mg/kg/day based on changes in brain morphometrics in the 

cerebellum. 

Uncertainty Factor (UF): 100 – 10x for interspecies extrapolation and 10x for intraspecies 

variation.

Comments about Study/Endpoint: This endpoint is considered appropriate based on the 

post-natal component of the DNT. 

3.3.5 Dermal Absorption

There are no dermal absorption studies available with acibenzolar-S-methyl. However, 

the dermal absorption rate for acibenzolar-S-methyl is estimated to be 40% by comparing 

maternal toxicity LOAEL (400 mg/kg/day) from an oral developmental toxicity study in rats 

(MRID 44014236) to the LOAEL (> 1000 mg/kg/day) from a dermal toxicity study in rats 

(MRID 44014233). [Note: A dermal absorption factor of 10% was used in the previous risk 

assessment of acibenzolar-S-methyl (D361893, 3/3/09). The DAF has been revised to 40% 

based on a reevaluation of the dermal and oral toxicity data.]

3.3.6 Dermal Exposure (Short and Intermediate-Term)

Selected Study: Developmental Neurotoxicity in Rats (MRID 44014236). 

See Section 3.2.3

Dose and Endpoint: 8.2 mg/kg/day based on an offspring NOAEL of 8.2 mg/kg/day and 

an offspring LOAEL of 82 mg/kg/day based on changes in brain morphometrics in the 

cerebellum. 

Uncertainty Factor (UF): 100 – 10x for interspecies extrapolation and 10x for intraspecies 

variation.

Comments about Study/Endpoint: Two acceptable dermal toxicity studies, including a 

dermal developmental study were available. However since neurological effects observed in the 

oral developmental neurotoxicity study are not measured in the dermal developmental study, the 

findings from the dermal study may not be protective of these neurological effects. Since an oral 

NOAEL was selected for dermal risk assessment, a dermal absorption factor of 10% should be 

used. This factor is based on the ratio of the dermal NOAEL of 1000 divided by the oral 

maternal LOAEL of 400 which equals 40%.
Page 19 of 53

3.3.7 Inhalation Exposure (Short and Intermediate-Term)

Selected Study: Developmental Neurotoxicity in Rats (MRID 44014236). 

See Section 3.2.3

Dose and Endpoint: 8.2 mg/kg/day based on an offspring NOAEL of 8.2 mg/kg/day and 

an offspring LOAEL of 82 mg/kg/day based on changes in brain morphometrics in the 

cerebellum. 

Uncertainty Factor (UF): 100 – 10x for interspecies extrapolation and 10x for intraspecies 

variation.

Comments about Study/Endpoint: Since an oral NOAEL was selected for inhalation risk 

assessment, an inhalation absorption factor of 100% should be used

3.3.8 Classification of Carcinogenic Potential

The Hazard Identification Assessment Review Committee (HIARC) classified 

acibenzolar-S-methyl as a “not likely” human carcinogen based on negative carcinogenicity

studies in rats and mice and on generally negative mutagenicity studies. 

[Note: The cancer classification has not been updated based on the EPA’s 2005 Guidelines for 

Carcinogen Risk Assessment.]

3.4 Margins of Exposure

A summary of target Levels of Concern for risk assessment is provided in Table 5.

Table 5. Target Levels of Concern/Margin of Exposure for Acibenzolar-S-Methyl

Route/Duration Short-Term

(1-30 Days)

Intermediate-Term

(1 - 6 Months)

Long-Term

(> 6 Months)

Occupational (Worker) Exposure

Dermal 100 100 N/A

Inhalation 100 100 N/A

Residential (Non-Dietary) Exposure

Oral 100 N/A N/A

Dermal 100 N/A N/A

Inhalation 100 N/A N/A

3.5 Recommendation for Aggregate Exposure Risk Assessments

When there are potential residential exposures to the pesticide, aggregate risk assessment 

must consider exposures from three major sources: oral, dermal and inhalation exposures. There 

are potential residential post-application exposure to adults via the dermal route and to children 

via dermal and incidental oral routes of exposure. Dietary, dermal and incidental oral endpoints 
Page 20 of 53

for acibenzolar-S-methyl are based on common toxicological effects for females 13-49 years old 

and children. Therefore, exposures from food and non-food oral and dermal routes should be 

aggregated for those subpopulations for this assessment. In addition, dermal, and inhalation 

exposures to should be aggregated for acibenzolar-S-methyl, because the same oral toxicity

endpoint was selected for both exposure routes. 

3.6 Summary of Endpoints Selected for Risk Assessment

Toxicological doses/endpoints selected for the acibenzolar-S-methyl risk assessment are 

provided in Tables 6 and 7.

Table 6. Summary of Toxicological Doses and Endpoints for Acibenzolar-S-methyl for Use in Dietary Human Health Risk 

Assessments

Exposure/Scenario Point of 

Departure

Uncertainty/FQPA 

Safety Factors

RfD, PAD, LOC 

for Risk 

Assessment

Study and Toxicological Effects

Acute Dietary 

(General Population)

NOAEL = 

8.2 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Acute RfD = 

0.082 mg/kg/day

aPAD = 0.082

mg/kg/day

Developmental Neurotoxicity Toxicity Study -

Rat 

Developmental LOAEL = 82 mg/kg/day based 

on changes in brain morphometrics in the 

cerebellum in offspring. 

Maternal LOAEL = was not observed NOAEL 

= 4000 mg/kg/day HDT

Chronic Dietary 

(Females 13-49 years

& Young Children)

NOAEL = 

8.2 

mg/kg/day

UFA= 10x.

UFH=10x

FQPA SF= 1x

Acute RfD = 

0.082 mg/kg/day

aPAD = 0.082 

mg/kg/day

Developmental Neurotoxicity Toxicity Study -

Rat 

Developmental LOAEL = 82 mg/kg/day based 

on changes in brain morphometrics in the 

cerebellum in offspring. 

Maternal LOAEL = was not observed 

NOAEL = 4000 mg/kg/day HDT

Chronic Dietary 

(Adult Males and 

Females 50+ yrs)

NOAEL = 

25 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Chronic RfD = 

0.25

mg/kg/day

cPAD = 0.25 

mg/kg/day

Chronic Toxicity - Dog; Co-critical; 

Chronic/Cancer - Rat & Mouse, Reproduction 

Toxicity - Rat 

LOAEL = 105 mg/kg/day based on hemolytic 

anemia with compensatory response. 

Incidental Oral NOAEL= 

8.2 

mg/kg/day

UFA= 10x

UFH=10x

Occupational 

LOC for MOE = 

100

Developmental Neurotoxicity Toxicity Study -

Rat 

Developmental LOAEL = 82 mg/kg/day based 

on changes in brain morphometrics in the 

cerebellum in offspring. 

Maternal LOAEL = was not observed 

NOAEL = 4000 mg/kg/day HDT

Dermal Short Term 

(1-30 days) 

DAF = 10%

NOAEL= 

8.2 

mg/kg/day

UFA= 10x

UFH=10x

Occupational 

LOC for MOE = 

100

Developmental Neurotoxicity Toxicity Study -

Rat 

Developmental LOAEL = 82 mg/kg/day based 

on changes in brain morphometrics in the 

cerebellum in offspring. 

Maternal LOAEL = was not observed 

NOAEL = 4000 mg/kg/day HDT
Page 21 of 53

Table 6. Summary of Toxicological Doses and Endpoints for Acibenzolar-S-methyl for Use in Dietary Human Health Risk 

Assessments

Exposure/Scenario Point of 

Departure

Uncertainty/FQPA 

Safety Factors

RfD, PAD, LOC 

for Risk 

Assessment

Study and Toxicological Effects

Inhalation Short 

Term (1-30 days)

NOAEL= 

8.2 

mg/kg/day

UFA= 10x

UFH=10x

Occupational 

LOC for MOE = 

100

Developmental Neurotoxicity Toxicity Study -

Rat 

Developmental LOAEL = 82 mg/kg/day based 

on changes in brain morphometrics in the 

cerebellum in offspring. 

Maternal LOAEL = was not observed 

NOAEL = 4000 mg/kg/day HDT

Cancer (all routes) A “not likely” human 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). UFL = use of a LOAEL to extrapolate a NOAEL. UFS = 

use of a short-term study for long-term risk assessment. UFDB = to account for the absence of key date (i.e., lack of a critical study). FQPA SF = 

FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure. LOC = level 

of concern. N/A = not applicable.

Table 7. Summary of Toxicological Doses and Endpoints for Acibenzolar-S-methyl for Use in Occupational Human Health 

Risk Assessments

Exposure/

Scenario

Point of 

Departure

Uncertainty 

Factors

Level of Concern 

for Risk 

Assessment

Study and Toxicological Effects

Dermal Short (1-30 days) 

and Intermediate (1-6 

months) Term

DAF = 40%

NOAEL= 

8.2

mg/kg/day

UFA= 10x

UFH=10x

Occupational LOC 

for MOE = 100

Developmental Neurotoxicity Toxicity Study - Rat 

Developmental LOAEL = 82 mg/kg/day based on 

changes in brain morphometrics in the cerebellum in 

offspring. 

Maternal LOAEL = was not observed 

NOAEL = 4000 mg/kg/day HDT

Inhalation Short (1-30 

days) and Intermediate (1-6 

months) Term

NOAEL= 

8.2

mg/kg/day

UFA= 10x

UFH=10x

Occupational LOC 

for MOE = 100

Developmental Neurotoxicity Toxicity Study - Rat 

Developmental LOAEL = 82 mg/kg/day based on 

changes in brain morphometrics in the cerebellum in 

offspring. 

Maternal LOAEL = was not observed 

NOAEL = 4000 mg/kg/day HDT

Cancer (all routes) A “not likely” human carcinogen

DAF = Dermal Absorption Factor 

3.7 Endocrine Disruption

EPA is required under the FFDCA, as amended by FQPA, to develop a screening 

program to determine whether certain substances (including all pesticide active and other 

ingredients) “may have an effect in humans that is similar to an effect produced by a naturally

occurring estrogen, or other such endocrine effects as the Administrator may designate.” 

Following recommendations of its Endocrine Disruptor and Testing Advisory Committee 

(EDSTAC), EPA determined that there was a scientific basis for including, as part of the 

program, the androgen and thyroid hormone systems, in addition to the estrogen hormone 

system. EPA also adopted EDSTAC’s recommendation that the Program include evaluations of 

potential effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that 
Page 22 of 53

effects in wildlife may help determine whether a substance may have an effect in humans, 

FFDCA authority to require the wildlife evaluations. As the science develops and resources 

allow, screening of additional hormone systems may be added to the Endocrine Disruptor 

Screening Program (EDSP). 

4.0 DIETARY AND DRINKING WATER EXPOSURE ASSESSMENT

4.1 Residue Chemistry Profile

4.1.1 Metabolism in Primary Crops

The nature of the residues in plants has been adequately delineated based on metabolism 

studies with lettuce, tomato, rice, wheat, and tobacco. The HED MARC has determined that the 

residues of concern in plants for tolerance expression are residues convertible to 

benzo(1,2,3)thiadiazole-7-carboxylic acid (CGA-210007), expressed as acibenzolar-S-methyl. 

For purposes of risk assessment, residues of the 4- and 5-hydroxy metabolites (CGA-324041 and 

CGA-323060) of CGA-210007 should also be considered. For this purpose, the toxicity of 

CGA-324041 and CGA-323060 should be considered to be equivalent to that of the parent 

compound acibenzolar-S-methyl. These residues occur in significant quantities in lettuce and 

tomato. At this time, acibenzolar-S-methyl does not have common metabolites with other 

agrochemicals. The residues of concern for drinking water are the same as those listed in the 

tolerance expression; that is, residues convertible to CGA-210007. Table 8 provides a summary

of the MARC decisions regarding residues of concern for acibenzolar-S-methyl. 

Table 8: Summary of MARC Decisions for Acibenzolar-S-methyl

Matrix Residues of Concern 1

For Risk Assessment 2 For Tolerance Expression

Plants Residues of acibenzolar-S-methyl, benzo(1,2,3) 

thiadiazole-7-carbothioic acid-S-methyl ester, 

convertible to benzo(1,2,3)thiadiazole-7-carboxylic acid 

(CGA-210007), expressed as acibenzolar-S-methyl &

4-hydroxy CGA-210007 (CGA-323060)

5-hydroxy CGA-210007 (CGA-324041)

Residues of acibenzolar-S-methyl, 

benzo(1,2,3) thiadiazole-7-carbothioic 

acid-S-methyl ester, convertible to 

benzo(1,2,3)thiadiazole-7-carboxylic 

acid (CGA-210007), expressed as 

acibenzolar-S-methyl

1

The residues of concern for drinking water are the same as those listed in the tolerance expression

2

If a future petition is received for rice, residues of CGA-379019 should be included in the risk assessment

4.1.2 Residue Analytical Methods

4.1.2.1 Enforcement Methods

An adequate method, HPLC/UV Method AG-671A, is available for tolerance 

enforcement. This method has undergone a successful tolerance method validation by the 

Analytical Chemistry Branch of BEAD. The method was forwarded to FDA for inclusion in 

PAM Volume II. The method consists of an initial hydrolysis with NaOH to convert 

acibenzolar-S-methyl to CGA-210007 followed by methanol extraction. Residues are then 

diluted with HCl and purified by a series of solid-phase extraction steps. Prior to HPLC/UV 

analysis, residues are partitioned into ethyl acetate, dried down, and redissolved in phosphoric 
Page 23 of 53

acid. This method has an LOQ of 0.02 ppm. The method includes optional detection via 

HPLC/MS, giving a means of residue confirmation. The HPLC/UV and LC/MS methods are 

adequate for collecting data on residues of acibenzolar-S-methyl in/on cucurbit vegetables and 

bulb onions, respectively. 

4.1.2.2 Multiresidue Methods

Data depicting the recovery of acibenzolar-S-methyl and its metabolite, CGA-210007, 

using FDA Multiresidue Methods, were previously submitted. Acibenzolar-S-methyl yielded 

adequate response to GLC analysis and was completely recovered through Protocols D and E. 

Partial recovery of CGA-210007 was achieved via Protocol B after derivatization.

4.1.3 Residues in Crops

Based on the results of the metabolism (radiotracer) study, conducted at the maximum 

proposed use rate, which demonstrated that the TRR levels in/on all raw agricultural 

commodities of cotton were < 5 ppb, HED concludes that the proposed use of BionTM 500FS as a 

cottonseed treatment meets EPA’s criteria for nonfood/nonfeed use classification, as defined in 

EPA’s Chemistry Science Advisory Council’s (ChemSAC’s) 28 October 1999 memorandum, 

Classification of Seed Treatments as Food or Nonfood Uses. No additional data on residues of 

acibenzolar-S-methyl in/on cotton grown from treated seed are needed to support the proposed 

use. 

4.2 Drinking Water Profile

4.2.1 Environmental Fate and Transport

Laboratory and field studies indicate that acibenzolar-S-methyl does not have a high 

potential to leach to ground water nor move to surface water based on its short resident times in 

soil and soil water. The major degradate observed was benzo[1,2,3]thiadiazole-7-carboxylic acid 

(CGA 210007) in the hydrolysis and soil photolysis studies (up to 100 percent). CGA-210007 

has a longer soil residence time, lower Freundlich Kd adsorption values, and is much more water 

soluble than acibenzolar-S-methyl, thereby exhibiting greater potential than the parent for lateral 

or vertical movement after application. Acibenzolar-S-methyl mainly degrades by photolysis and 

microbial action. Aqueous and soil photolysis irradiated half lives for parent are 0.6 hours and 1 

day, respectively. The aerobic soil metabolism, anaerobic aquatic metabolism and aerobic aquatic 

half lives are 5.3 hours, 4.0 and < 1 day(s) respectively. Field dissipation half-lives ranged from 

< 1 to 27 days. Under aerobic soil, aerobic aquatic, and anaerobic aquatic conditions acibenzolar 

quickly degrades to CGA 210007. CGA 210007 is in its anionic form at environmentally

significant pH's (pH 6-9) and appears to be more soluble than its parent, although measured at 

much lower pH’s (approx. 225 ppm at 250C pH 3.6-3.8 v. 7.7 ppm at 250C pH 7.5-7.9). CGA 

210007 has longer resident field times than parent (aerobic soil half-life at 16.5 days) and based 

on the batch equilibrium and aged soil column leaching studies, is considerably more mobile. 

Acibenzolar is not considered a bioconcentrate nor is it highly bioaccumulative. 
Page 24 of 53

4.2.2 Estimated Drinking Water Concentrations 

Drinking water residues provided by the Environmental Fate and Effects Division 

(EFED) (D351609, R. Miller, 8/8/08; D380135, 7/9/10) were incorporated directly into the acute 

and chronic dietary analyses (“water, direct, all sources” and “water, indirect, all sources EFED 

generated the surface water and ground water estimates using the Pesticide Root Zone Model 3 

(PRZM3; ver. 3.12.2; 2-May-2005)/Exposure Analysis Modeling System (EXAMS; ver. 

2.98.04.06; 25-Apr-2005) and Screening Concentration in Ground Water (SCIGROW; Tier 1) 

models, respectively. The residues of concern for drinking water include acibenzolar-S-methyl 

and residues convertible to CGA-210007. Based on the EFED drinking water analysis conducted 

for the proposed new use of acibenzolar-S-methyl on cotton and turf, EDWCs from these uses 

will be less than the EDWCs for the existing use on cucurbits. Therefore estimated EDWCs for 

use of acibenzolar-S-methyl on cucurbits were used for the drinking water assessment because 

this use represents the highest use rate of the existing and proposed registered uses. The SCIGROW estimated ground water drinking water concentrations for acibenzolar is not expected to 

exceed 4.08 x 10-5μg/L and CGA 210007 is not expected to exceed 0.557 μg/L. Surface water 

EDWCs for acibenzolar-S-methyl, which were used in the exposure assessment, are provided in 

Table 9. CGA-210007 drinking water residues were included in the dietary exposure assessment 

as acibenzolar-S-methyl equivalents. 

Table 9. EDWCs for use in screening the Acibenzolar-S-Methyl Human Health Risk Assessment 

Drinking Water 

Source Chemical Acute (μg/L) NonCancer 

Chronic (μg/L)

Cancer Chronic(μg/L)

Surface Water Acibenzolar1

0.74 0.10 0.05

Surface Water CGA 2100072

14.21 9.48 5.47

1 Aerial application method

2 Degradation product formed after application

4.3 Dietary and Drinking Water Exposure and Risk

Refined acute and screening-level chronic dietary and drinking water exposure and risk 

assessments were conducted using the Dietary Exposure Evaluation Model with the Food 

Commodity Intake Database (DEEM-FCIDTM). Dietary risk assessment incorporates both 

exposure and toxicity of a given pesticide. For acute and chronic dietary assessments, the risk is 

expressed as a percentage of a maximum acceptable dose (i.e., the dose which HED has 

concluded will result in no unreasonable adverse health effects). This dose is referred to as the 

population adjusted dose (PAD). The PAD is equivalent to the reference dose (RfD) divided by

the additional Safety Factor, if applied. For acute and non-cancer chronic exposures, HED is 

concerned when estimated dietary risk exceeds 100% of the PAD. 

Available lettuce metabolism data for a 7-day PHI were used to estimate the relative 

abundance of the hydroxy metabolites (CGA-323060 and CGA-324041) to the residues of 

acibenzolar-S-methyl convertible to the benzo(1,2,3) thiadiazole-7-carboxylic acid (CGA210007). Based on the lettuce metabolism data, a factor of 1.5X was applied to estimates of 

acibenzolar-S-methyl residues to account for all of the residues of concern for dietary risk 

(including CGA-323060 and CGA-324041). 
Page 25 of 53

4.3.1 Acute Dietary and Drinking Water Analysis

A refined (probabilistic) acute dietary exposure analysis was performed for the general 

population and all population subgroups. The acute analysis assumed a distribution of residues 

based on field trial data. Empirical and DEEM default processing factors were used to modify

the field trial data. Maximum screening-level percent crop treated estimates were used for 

commodities for which data were available. If no percent crop treated data were available, 100% 

crop treated was assumed. The acute analysis incorporated the 1 in 10 year peak surface drinking 

water estimate from application of acibenzolar-S-methyl to cucurbit vegetables. Acute dietary

risk estimates are not of concern for general population or other population subgroups. The 

subgroup with the highest risk estimate was children 3-5 years old with a 99.9th percentile acute 

exposure estimates of 38% of the aPAD. The 99.9th percentile aPAD for the general U.S. 

population was 18%. 

Table 10: Summary of Acute Dietary Exposure and Risk for Acibenzolar-S-Methyl

Population Subgroup aPAD (mg/kg/day) Acute (99th Percentile)

Exposure (mg/kg/day) % aPAD

General U.S. Population

0.082

0.0145 18

All Infants (< 1 year old) 0.0136 17

Children 1-2 years old 0.0250 30

Children 3-5 years old 0.0307 37

Children 6-12 years old 0.0204 25

Youth 13-19 years old 0.0152 19

Adults 20-49 years old 0.0094 11

Adults 50+ years old 0.0112 14

Females 13-49 years old 0.0096 12

4.3.2 Chronic Dietary and Drinking Water Analysis

A conservative chronic dietary exposure analysis was performed for the general U.S. 

population and various population subgroups. Tolerance level residues and 100 crop treated 

assumptions were used. DEEM default and empirical processing factors were used to modify the 

tolerance values. The chronic analysis incorporated the 10 year average surface drinking water 

estimate from application of acibenzolar-S-methyl to cucurbit vegetables. The population 

subgroups females 13-49 and young children had a more protective chronic population adjusted 

dose (cPAD, 0.082 mg/kg/day) than the general U.S. population and all other population 

subgroups (0.25 mg/kg/day). Chronic dietary risk estimates are not of concern for general 

population or other population subgroups. The subgroups with the highest risk estimate were 

children 1-2 and 3-5 years old with a cPAD of 11%. The cPAD for the general U.S. population 

was 2%. 
Page 26 of 53

Table 11: Summary of Chronic Dietary Exposure and Risk to Female and Child Population for 

Acibenzolar-S-Methyl 

Population Subgroup cPAD (mg/kg/day)

Chronic

Exposure (mg/kg/day) % cPAD

Females 13-49 years old

0.082

0.0038 5

All Infants (< 1 year old) 0.0043 5

Children 1-2 years old 0.0093 11

Children 3-5 years old 0.0088 11

Children 6-12 years old 0.0059 7

Table 12: Summary of Chronic Dietary Exposure and Risk to Adults 50+ and Adult Males (13+)

Acibenzolar-S-Methyl

Population Subgroup cPAD (mg/kg/day) Chronic

Exposure (mg/kg/day) % cPAD

General U.S. Population

0.25

0.0045 2

Males 13-19 0.0042 2

Males 20+ 0.0038 2

Adults 50+ years old 0.0040 2

5.0 RESIDENTIAL EXPOSURE AND RISK ASSESSMENT

5.1 Exposure Scenarios

The proposed uses associated with this action are for application of acibenzolar-S-methyl

to turfgrass on golf courses, collegiate athletic fields, and lawns around commercial and 

industrial buildings. Based on the use patterns specified on the label, acibenzolar-S-methyl could 

be used on lawns around apartment complexes. Therefore, standard residential lawn and turf 

handler and post-application exposure scenarios were assessed for the proposed new use. 

 

5.1.1 Handler Exposure Scenarios 

Based on the number of seasonal applications indicated on this product label, and 

information provided by the registrant, residential handler exposures are expected to be short- (1-

30 days) and intermediate-term (1-6 months) in duration. The following residential handler 

exposure scenarios were assessed:

1) Low Pressure Handwand (dry flowable and soluble liquid) formulation to 

Lawn/Turf.

2) Hose-end Sprayer (dry flowable and soluble liquid) formulation to Lawn/Turf.

5.1.2 Post-Application Exposure Scenarios

Dermal exposure was assessed for adult and child recreational golfer and residential 

activities on treated turf. Incidental oral exposure (hand to mouth, object to mouth, and soil 

ingestion) was assessed for toddlers. 
Page 27 of 53

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

exposure assessment was not performed for acibenzolar-S-methyl. However, volatilization of 

pesticides may be a potential source of post application inhalation exposure to individuals nearby

to pesticide applications. The Agency sought expert advice and input on issues related to 

volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific

Advisory Panel (SAP) in December 2009. The Agency received the SAP’s final report on March 

2, 2010 and is in the process of evaluating the SAP report. The Agency may, as appropriate, 

develop policies and procedures to identify the need for and, subsequently, the way to incorporate

post application inhalation exposure into the Agency's risk assessments. If new policies or 

procedures are put into place, the Agency may revisit the need for a quantitative post application

inhalation exposure assessment for acibenzolar-S-methyl. 

5.2 Exposure Data and Assumptions 

Maximum application rates for all of the exposure scenarios assessed are based on 

information provided in the proposed acibenzolar-S-methyl label. Based on the label, the 

maximum single application rate is 0.22 lbs ai per acre. The post-application risk assessment is 

based on generic assumptions from the Recommended Revisions to the Residential SOPs, and 

recommended approaches by HED’ Science Advisory Council for Exposure (ExpoSAC). The 

following standard exposure assumptions were used in estimating post-application risks.

5.2.1 Handler Exposure Scenarios

• Average body weight of an adult handler is 60 kg.

• Exposure duration is short-term. 

• Dermal absorption factor = 40%

• Maximum application rates as determined by label

• SOP daily volumes handled and/or area treated used for the scenarios assessed are 0.5

acres treated per day

5.2.2 Post-Application Exposure Scenarios

• Average adult body weight is 60 kg

• Average older child (golfer) body weight is 39 kg

• Average young child body weight is 15 kg

• Dermal absorption factor = 40%

Golfers & Homeowners:

• Exposure is assumed to occur on the day of application (day 0)

• Turf Transferrable residue is 5% of the application rate for the fraction initially available. 

• Transfer coefficient is 500 cm2/hour for golfers 

 • Exposure duration is 4 hours per day for golfers and 8 hours per day for homeowners

Child Hand-to-mouth

• Exposure is assumed to occur on the day of application (day 0) 

• Saliva extraction factor is 50 percent.
Page 28 of 53

• Surface portion of hand put in mouth is 20 cm2.

• Hand-to-mouth exposure frequency is 20 times per hour.

• Exposure duration is 2 hours for outdoor exposures.

Toddler Object to Mouth Scenario

• Object to mouth transfer efficiency is equal to 20% of the application rate.

• Surface area from mouthing turf or a small object is 25 cm2.

Toddler Incidental Soil Ingestion Scenario

• Soil ingestion rate is 100 mg/day .

• Fraction of ai available in uppermost cm of soil (fraction/cm) is 100 percent based on soil 

incorporation into top 1 cm of soil after application.

5.3 Residential Exposure and Risk Estimates

5.3.1 Handler Exposure and Risk

A target LOC or MOE of 100 is considered adequate residential exposure and risk. All 

residential exposures are assessed as short-term based on label prescribed uses. Exposure and 

risk estimates indicate MOEs are not of concern (MOEs > 100) at the maximum use rate for the 

residential post-application exposure scenario assessed. A summary of residential handler 

exposure and risk calculations, assumptions, and results is provided in Table 13.

Table 13: Residential Handler Exposure Assessment Acibenzolar-S-Methyl Application to Lawns/Turf

Exposure Scenario 2Application

Rate

(lb ai/A)

3Area 

Treated

(A/day)

1Dermal

Unit 

Exposure

(mg/lb ai)

Inhal Unit 

Exposure 

(g/lb ai)

5Dermal

Daily Dose

(mg/kg/d)

5

Inhal

Daily Dose

(mg/kg/d)

Short 

Term

MOE4

Mixing, Loading Applying

Low Pressure Handwand

(Soluble Liquid)

0.022 0.5

100 30 0.0073 0.000006 1100

Mixing, Loading, and 

Applying Hose-end Sprayer

(Dry Flowable)

11 17 0.0008 0.000003 10000

 1. Dermal unit exposure values. Values are reported in the PHED Surrogate Exposure Guide dated August 1998. 

2. Application rates are based on maximum values found in proposed labels. Daily area treated is based on the area or gallons that 

can be reasonably applied in a single day for each exposure scenario of concern based on the application method and 

formulation/packaging type. (Standard EPA/OPP/HED values).

4. Daily Dose (mg/kg/day) Dermal = Unit Exposure * % Absp * Appl. rate * Area treated} / BW-60 kg. {Where: dermal 

absorption. is assumed to be 40%}. Inhalation = Unit Exposure * Area treated/BW

5. Short -Term MOE = NOAEL (8.2 mg/kg/day)/Dermal + Inhalation Daily Dose. The LOC is 100.

5.3.2 Post-Application Exposure and Risk

A target LOC or MOE of 100 is considered adequate residential exposure and risk. All 

residential exposures are assessed as short-term based on label prescribed uses. Exposure and 

risk estimates indicate MOEs are not of concern (MOEs > 100) at the maximum use rate for the 

residential post-application exposure scenario assessed. A summary of residential post-
Page 29 of 53

application exposure and risk calculations, assumptions, and results is provided in Tables 14 and 

15.

Table 14. Estimated Acibenzolar-S-Methyl Exposure & MOEs for Post-application Dermal Exposure to 

Treated Lawn/Golf Course Turf LOC/MOE = 100

Exposure Scenario AR (lb ai/A) TC (cm2/hr)

Exposure Duration 

(hrs/day)

Dermal dose

(mg/kg/day)

Dermal 

MOE

Adult Golfers

0.022

500 4 0.000164 50000

Child Golfer 500 4 0.000253 30000

Adult Lawn Activities 14500 8 0.00135 6000

Child Lawn Activities 5200 8 0.00194 4000

1 Application rates are based on maximum values based on proposed label.

2 TTR or DFR (mg/cm2

) = Application Rate (lb ai/A) x CF (4.54E+5 mg/lb) x CF (2.47E-8 A/ cm2) x 5% (initial fraction of ai retained on turf) 

Application rates are based

3 TC cm2

/hr = Transfer coefficients and associated activities (ExpoSAC Policy Memo #003.1)

4 Dermal Dose (mg/kg/day) = TTR (mg/cm2

) x TC (cm2/hr) x 4 (hrs/day)/70 kg (body weight)

8 Dermal MOE = short-term endpoint for dermal (NOAEL 8.2 mkd)/Daily Dermal Dose

Table 15. Post-application Incidental Ingestion Risks to Toddlers Reentering Treated Lawns

Exposure 

Scenario AR (lb ai/A) Daily Oral Dose 

(mg/kg/day) Oral MOE Aggregate Oral and Dermal MOE

Hand-to-Mouth

0.022

0.00033 25000

Object-to-Mouth 0.00008 100000 9000

Soil Ingestion 0.000001 >1000000

Hand To Mouth Calculation

PDR(t) (mg/day) = (HTE(t) (μg/cm2) * SEF * SA * Freq * ED/1000 (μg/mg)

where:

PDR = Potential Dose Rate at time (t) attributable for activity in a previously treated area (mg/day)

HTE = Hand Transfer Efficiency at time t = 5% of Application Rate (μg/cm2) Application rate = 0.2% ai, 3 seconds per cubic yard, 1.5 

g/sec, all spray settles to turf (MRID 47119801)

SEF = Saliva Extraction Factor (50%)

SA = Surface Area of Two Fingers (20 cm

2

)

Freq = Frequency of Hand to Mouth Events (20)

ED = Exposure Duration in hours (2 hr/day)

t = Postapplication Day on which exposure is being assessed (day 0)

MOE = Short Term Oral NOAEL (8.2 mkd)/Daily Oral Dose (mg/kg/day)

Object to Mouth Calculation

PDR(t) (mg/day) = (DFR(t) (μg/cm2) * SA/1000 (μg/mg)

where:

PDR = Potential Dose Rate at time (t) attributable for activity in a previously treated area (mg/day)

DFR(t)= Dislogeable Foliar Residue at time t = 20% of Application Rate (μg/cm2) APR = 1.1 μg/cm2

SA = Surface Area of grass or toy mouthed by toddler (25 cm2day)

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

MOE = Short Term Oral NOAEL(8.2 mkd)/[Daily Oral Dose (mg/kg/day) MOEs are reported to two significant figures

Soil Ingestion Calculation

PDR(t) (mg/day) = (SRt * IgR * CF1)

where:

PDR = Potential Dose Rate - nondietary ingestion rate from contact with treated surface (mg/day)

SRt = Soil Residue on day "t" (μg/g) = Application Rate (μg/cm2) * 1/cm * 0.67 cm3/g soil [1/cm is fraction of ai available in 

uppermost cm of soil]

IgR = Ingestion Rate of soil (mg/day); (100 mg/day)

CF1 = Weight unit conversion factor (1E-6 g/μg)

t = Postapplication Day on which exposure is being assessed, assumed to be day zero

MOE = Short Term Oral NOAEL (8.2 mkd)/[Daily Oral Dose (mg/kg/day). MOEs are reported to two significant figures

Aggregate Oral and Dermal MOE = Short Term Oral NOAEL/Daily Oral Dose (all incidental oral) + Daily Dermal Dose

6.0 AGGREGATE EXPOSURE AND RISK ASSESSMENT 

In accordance with the FQPA, when there are potential residential exposures to a 
Page 30 of 53

pesticide, aggregate risk assessment must consider exposures from three major routes: oral, 

dermal, and inhalation. There are three sources for these types of exposures: food, drinking 

water, and residential uses. In an aggregate assessment, exposures from relevant sources are 

added together and compared to quantitative estimates of hazard (e.g., a NOAEL or PAD), or the 

risks themselves can be aggregated. When aggregating exposures and risks from various sources,

HED considers both the route and duration of exposure.

6.1 Acute & Chronic Aggregate Risk

Acute and chronic aggregate exposures include food plus drinking water exposures. 

Acute and chronic aggregate risks are not of concern.

6.2 Short- Term Aggregate Risk

To assess short--term aggregate risk likely to result from the new and existing uses, HED 

combined average food and water exposure values with estimates of residential exposure for 

adult handlers and with residential exposure for adult and child post-application activities Tables 

16 and 17. Exposure for adult and child golfers was used to aggregate adult post-application 

dermal exposure with dietary and drinking water exposure. The aggregate exposure assessment 

for children combines dermal and incidental oral post-application exposure with food and water 

exposure. 

Table 16. Short-Term Aggregate Risk Calculations - Residential Handler LOC =100

Population Subgroup

Average

Food & Water Exposure

mg/kg/day

Residential

Exposure1

mg/kg/day

Aggregate MOE

(food and

residential)2

Females 13-49 yrs 0.0038 0.0073 700

1 Residential Exposure = [Dermal exposure + Inhalation Exposure]. 

2 Aggregate MOE = [NOAEL (8.2 mg/kg/day (Avg Food & Water Exposure + Residential Handler Exposure)]

Table 17. Short-Term Aggregate Risk Calculations - Residential Post-Application Exposure LOC =100

Population Subgroup

Average

Food & Water Exposure

mg/kg/day

Residential 

Exposure1

mg/kg/day

Aggregate MOE

(food and

residential)2

Females 13-49 yrs 0.0038 0.00135 1600

Children 6-12 yrs 0.0059 0.00194 1000

Children 1-2 yrs 0.0093

0.0009

800

Children 3-5 yrs 0.0088 850

1 Residential Exposure = [Dermal exposure + Inhalation Exposure]. 

2 Aggregate MOE = [NOAEL (8.2 mg/kg/day (Avg Food & Water Exposure + Residential Exposure)] Adult residential postapplication exposure from golfer scenario. Child residential exposure includes incidental oral and dermal exposures.
Page 31 of 53

7.0 OCCUPATIONAL EXPOSURE AND RISK

7.1 Exposure Scenarios

Occupational handler and post-application exposure scenarios were assessed for the risk 

assessment of the proposed new uses on cotton seed and turf. 

7.1.1 Handler Exposure Scenarios

The term “handler” applies to individuals who mix, load, and apply the pesticide product. 

The following handler exposure scenarios were assessed for proposed new acibenzolar-S-methyl

uses.

7.1.1.1 Application to Turf

- Mixing and Loading a liquid formulation for groundboom application

- Applying a liquid formulation with groundboom equipment.

- Mixing, Loading, and Applying a liquid formulation with handgun spraying 

equipment.

7.1.1.2 Seed Treatment

- Loading/Applying flowable concentrate for seed treatment 

- Sewing flowable concentrate 

- Bagging flowable concentrate 

- Multiple Activities with flowable concentrate 

7.1.2 Post-Application Exposure Scenarios

The following post-application exposure scenarios were assessed for proposed new 

acibenzolar-S-methyl uses.

7.1.2.1 Turf Application

- Mowing

- Hand weeding, transplanting

- Golfing

7.1.2.2 Seed Treatment

- Seed Planting - Flowable concentrate for Seed treatment applications {single layer 

clothing with gloves).
Page 32 of 53

7.2 Occupational Exposure Data and Assumptions

7.2.1 Exposure Data

Maximum application rates for all of the exposure scenarios assessed are based on 

information provided in the acibenzolar-S-methyl labels for the proposed new uses. The 

maximum single application rate for turf is 0.022 lbs ai per acre. The maximum application rate 

for seed treatment is 9.9 x 10-6lb ai/lb seed. Data from the Pesticide Handlers Exposure

Database (PHED) was used to assess handler and post-application exposures in the absence of 

chemical-specific data. The transfer coefficients used in the post-application exposure 

assessment are from an interim transfer coefficient guidance document developed by HED’s 

Science Advisory Council for Exposure using proprietary data from the Agricultural Re-entry

Task Force (ARTF) data base (SOP #3.1). Post-application exposures were assessed for the 

proposed new uses. There are no compound specific data with which to estimate postapplication exposures to agricultural workers. Estimates of post-application re-entry exposure to 

agricultural workers are based upon the EXPOSAC Standard Operating Procedures (SOPs) (3.1, 

Reference 4). This SOP lists a number of possible post-application agricultural activities for the 

proposed crop uses that might result in post-application. Post-application exposure involving 

Commercial Seed treatment using acibenzolar-s-methyl consists of a “Planting Treated Seed” 

activity. HED’s SOP 14 is the data source for this “planting scenario” (which includes exposure 

to pesticide treated seed during both the loading of hoppers and driving the equipment). 

7.2.2 Exposure Assumptions

The following standard exposure assumptions were used in estimating risks to workers 

from exposure to acibenzolar-S-methyl for the proposed new uses on onion and cucurbits.

7.2.2.1 Handler Exposures

• Average body weight of an adult handler is 60 kg.

• Exposure duration is short-term and intermediate-term for all workers assessed. 

• Maximum application rates as determined by label review were used for all types and 

methods of application.

• SOP daily volumes handled and/or area treated used for the scenarios assessed are: 

- 80 acres treated per day for groundboom mixer/loader and applicator for 

commercial turf applications (sod farm, athletic fields, commercial/industrial

lawns) 

- 40 acres treated per day for groundboom mixer/loader and applicator for golf 

course turf applications.

- 5 acres treated per day for handgun sprayer mixing, loading, and applying to turf

areas.

- Seed treatment application frequency is one event/application per season.

- Total amount of seed treated is 160,000 lb/season for commercial treatment

- Total amount of seed treated is 3600 for on farm treatment
Page 33 of 53

7.2.2.2 Post Application Exposures

• Average body weight is 60 kg.

• Transferrable residue is application rate times the fraction initially available (20%). 

• Maximum transfer coefficient for post-application activities is 2500 cm2/hour (hand 

harvesting).

• Exposure duration is 8 hours day.

• Exposure is assumed to occur on the day of application (day 0).

• 72,000 lbs seed/season can be planted.

7.3 Occupational Exposure and Risk Estimates

7.3.1 Handler Exposure and Risk Estimates

A target LOC or MOE of 100 is considered adequate for inhalation and dermal exposure. 

All worker exposures are assessed as short-and intermediate-term based on label prescribed uses 

and expected exposure durations. Dermal and inhalation exposures to workers should be 

aggregated for acibenzolar-S-methyl because the same oral toxicity endpoint was selected for 

these exposure routes. Exposure and risk estimates indicate MOEs are not of concern (MOEs > 

100) at the maximum use rate for occupational handler activities for the proposed new uses. A 

summary of occupational handler exposure and risk calculations, assumptions, and results is 

provided in Tables 18 and 19.

Table 18: Short/Intermediate-Term Occupational Handler Exposure and Risk for Acibenzolar-S-Methyl

Exposure 

Scenario 1 Crop or Target

App 

Rate 

(lb ai/A)2

Acres 

Treated 

Daily

Unit Exposure3 Dose (mg/kg/Day)4,5 MOEs6

Dermal 

(mg/lb ai)

Inhalation 

(μg/lb ai) Dermal Inhalation

Combined 

Dermal + 

Inhalation

Mixer/Loader

Groundboom

(Open Cab) 

Commercial/

Industrial Lawns/Turf 0.022

80

2.9 1.2

0.0340 3.5E-06 240

Golf Course Turf 40 0.0170 1.7E-06 480

Mixer/Loader/Applicator

Handgun 

Sprayer 

Commercial/

Industrial Lawns/Turf

Golf Course Turf

0.022 5 0.5 1.9 0.0004 3.5E-06 22000

Applicator

Groundboom 

(Open Cab)

Commercial/

Industrial Lawns/Turf 0.022

80

0.014 0.00074

0.00016 2.0E-05 44000

Golf course Turf 40 0.000082 1.1E-05 88000

1 Use patterns are from the proposed labels 

2 Application rates are based on maximum values based on proposed label. Most application rates upon which the 

analysis is based are presented as lb ai/A. In some cases, the application rate is based on applying a solution at 

concentrations specified by the label (i.e., presented as lb ai/gallon). 

3 Baseline unit exposures. Values are reported in the PHED Surrogate Exposure Guide dated August 1998 or are 

from data submitted by the Outdoor Residential Exposure Task Force dated May 2000. 
Page 34 of 53

4

Inhalation dose (mg/kg/day) = [unit exposure (ug/lb ai) * 0.001 mg/ug unit conversion * Inhalation absorption 

(100%) * Application rate (lb ai/acre or lb ai/gallon) * Daily area treated/amount handled (acres or gallons)] / Body 

weight (60 kg).

5 Dermal Dose (mg/kg/day) = [unit exposure (mg/lb ai) * Application rate (lb ai/acre or lb ai/gallon) * Daily area 

treated/amount handled (acres or gallons) * Dermal Absorption Factor (10%)] / Body weight (60 kg).

6

 Aggregate MOE = NOAEL (8.2 mkd)/Daily Inhalation Dose + Daily Dermal Dose

Table 19. Commercial Seed Treatment Handler Exposure and Risk for Acibenzolar-S-Methyl

Exposure 

Scenario

a

Dermal 

Exp.b

(mg/lb ai)

Inhl.

Exp.c 

(ug/lb ai)

Crop

App. Rate

(lb ai/lb 

seed)

Amnt. 

Treatedd

(lbs. seed)

Dermal

Dosee

(mg/kg)

Inhl.

Dosef

(mg/kg)

Combined

Doseg

(mg/kg)

M0Eh

Loader/ Applicator

Single Layer 

w/ gloves 0.023 0.34 Cotton Seed 0.0000099 160,000 0.00024 0.000009 0.00034 33000

Sewer

Single Layer 

w/no gloves 0.0062 0.23 Cotton Seed 0.0000099 160,000 0.00007 0.0000061 0.0.00007 12000

Bagger

Single Layer 

w/ no gloves

0.0091 0.16 Cotton 

Seed 0.0000099 160,000 0.0001 0.0000042 0.0001 81000

Multiple Activities

Single Layer 

w/ gloves 0.042 1.6 Cotton Seed 0.0000099 160,000 0.0004 0.000042 0.0004 16000

On Farm Treatment

Single Layer 

w/ gloves 12.6 1.2 CottonSeed 0.0000099 3600 0.0030 0.0000007 0.003 2700

a. PPE (Personal Protection Equipment) 

b. Dermal Unit Exposure is characterized with existing table.

c. Inhalation Exposure is based on a Baseline exposure scenario (no respiratory protection). 

d. Amount/Seed treated values are based on label specific information (EPA Reg. No. 100-889)

e. Dermal dose (mg/kg/event) = [unit dermal exposure (mg/lb ai) * dermal absorption (0.10) * application rate (lb ai/lb seed) * Amount treated / 

body weight (60 kg)].

f. Inhalation dose (mg/kg/event) = [unit exposure (kg/lb ai) * (1mg/1000 kg) conversion * appl. rate (lb ai/lbs seed) * Amount treated / body weight 

(60 kg)].

g. Combined event dose = event dermal dose + event inhalation dose.

h. MOE = NOAEL (mg/kg/d) / combined event dose. UF = 100.

I. Gloves used for loading only.

7.3.2 Post-Application Exposure and Risk Estimates

A target LOC or MOE of 100 is considered adequate for dermal exposure. Exposure and 

risk estimates indicate MOEs are not of concern (MOEs > 100) at the maximum use rate for 

occupational post-application exposure activities for the proposed new uses. A summary of postapplication exposure and risk calculations, assumptions, and results is provided in Table 20 and 

21.
Page 35 of 53

1 Maximum application rate from proposed label 

 2 DAT = Days after treatment needed to reach the LOC of 100; DAT 0 = the day of treatment/ assumed to be approx. 12 hours. 

 3 TTR (μg/cm2

) = Turf Transferable Residues corresponding to DAT, based on 20% of application rate.

 4 TC (cm2

/hr) = Transfer Coefficients and associated activities from ExpoSAC Policy Memo #003.1, 8/17/2000.

 5 MOE = MOE on the corresponding DAT. MOE = NOAEL / Daily Dose. 

 Daily Dose = [(TTR x TC x 10% Dermal absorption x 8-hr Exposure Time)] / [(CF: 1000 μg/mg) x (60-kg Body Weight) 

 Short-/intermediate-term NOAEL = 8.2 mg/kg/day. The LOC is 100

Table 21. Seed Planter Exposure and Risk for Acibenzolar-S-Methyl

Exposure 

Scenario

a

Dermal 

Exp.b

(mg/lb ai)

Inhl.

Exp.c 

(ug/lb ai)

Crop

App. 

Rate

(lb ai/lb 

seed)

Amnt. 

Treatedd

(lbs. seed)

Dermal

Dosee(mg/kg)

Inhl.

Dosef

(mg/kg)

Combined

Doseg

(mg/kg)

M0Eh

Seed PlanterI

Single Layer 

w/ no gloves 0.25 3.4 Cotton Seed 0.0000099 3600 0.00006 0.00009 0.00015 55000

a. PPE (Personal Protection Equipment) 

b. Dermal Unit Exposure is characterized with existing table.

c. Inhalation Exposure is based on a Baseline exposure scenario (no respiratory protection). 

d. Amount/Seed treated values are based on label specific information (EPA Reg. No. 100-889)

e. Dermal dose (mg/kg/event) = [unit dermal exposure (mg/lb ai) * dermal absorption (0.10) * application rate (lb ai/lb seed) * Amount treated / 

body weight (60 kg)].

f. Inhalation dose (mg/kg/event) = [unit exposure (kg/lb ai) * (1mg/1000 kg) conversion * appl. rate (lb ai/lbs seed) * Amount treated / body weight 

(60 kg)].

g. Combined event dose = event dermal dose + event inhalation dose.

h. MOE = NOAEL (mg/kg/d) / combined event dose. UF = 100.

I. Gloves used for loading only.

8.0 CUMULATIVE RISK

Section 408(b)(2)(D)(v) of FFDCA requires that, when considering whether to establish, 

modify, or revoke a tolerance, the Agency consider “available information” concerning the 

cumulative effects of a particular pesticide's residues and “other substances that have a common 

mechanism of toxicity.”

EPA does not have, at this time, available data to determine whether acibenzolar-Smethyl has a common mechanism of toxicity with other substances. Unlike other pesticides for 

which EPA has followed a cumulative risk approach based on a common mechanism of toxicity, 

EPA has not made a common mechanism of toxicity finding as to acibenzolar-S-methyl and any

other substances and, acibenzolar-S-methyl does not appear to produce a toxic metabolite 

produced by other substances which have tolerances in the U. S. For the purposes of this 

tolerance reassessment action, therefore, EPA has not assumed that acibenzolar-S-methyl has a 

common mechanism of toxicity with other substances. For information regarding EPA’s efforts 

Table 20. Summary of Estimated Occupational Post-application MOEs for Turf

Crop

Application 

Rate

(lb ai/A) 1

DAT2 TTR 3

(μg/cm2)

TC 4

(cm2/hr) Activity 4 Short-/IntTerm MOE5

Turf 0.022 0 0.012

500 Mowing 32500

16500 Hand weeding, transplanting 1000

500 Golfing 32500
Page 36 of 53

to determine which chemicals have a common mechanism of toxicity and to evaluate the 

cumulative effects of such chemicals, see the policy statements released by EPA’s OPP 

concerning common mechanism determinations and procedures for cumulating effects from 

substances found to have a common mechanism on EPA’s website at 

http://www.epa.gov/fedrgstr/EPA_PEST/2002/January/Day_16/.

9.0 DATA NEEDS

9.1 Toxicology Data Requirements 

- Immunotoxicity (GLN 870.7800)

- Battery of mutagenicity studies performed on technical-grade acibenzolar-S-methyl 

prepared by the thiazole production process. 

- Ames assay using the technical-grade acibenzolar-S-methyl prepared by the thiazole 

production process - including both plate incorporation and pre-incubation. (GLN 

870.5100, 870.5300, 870.375, 870.900)
Page 37 of 53

APPENDICES

1.0 TOXICOLOGY DATA SUMMARY

1.1 Guideline Data Requirements

Table 1. Guideline Data Requirements

Test Technical

Required Satisfied

870.1100 Acute Oral Toxicity.......................................................

870.1200 Acute Dermal Toxicity ..................................................

870.1300 Acute Inhalation Toxicity..............................................

870.2400 Primary Eye Irritation....................................................

870.2500 Primary Dermal Irritation ..............................................

870.2600 Dermal Sensitization......................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent)...............................................

870.3150 Oral Subchronic (nonrodent).........................................

870.3200 21-Day Dermal ..............................................................

870.3250 90-Day Dermal ..............................................................

870.3465 90-Day Inhalation..........................................................

yes

yes

yes

no

yes

yes

yes

yes

-

yes

870.3700a Developmental Toxicity (rodent)...................................

870.3700b Developmental Toxicity (nonrodent).............................

870.3800 Reproduction .................................................................

yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent)..............................................

870.4100b Chronic Toxicity (nonrodent)........................................

870.4200a Oncogenicity (rat)..........................................................

870.4200b Oncogenicity (mouse)....................................................

870.4300 Chronic/Oncogenicity....................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.5100 Mutagenicity—Gene Mutation - bacterial .....................

870.5300 Mutagenicity—Gene Mutation - mammalian ................

870.5375 Mutagenicity—Structural Chromosomal Aberrations ...

870.5900 Mutagenicity—Other Genotoxic Effects.......................

yes

yes

yes

yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotox. (hen) .....................................

870.6100b 90-Day Neurotoxicity (hen)...........................................

870.6200a Acute Neurotox. Screening Battery (rat) .......................

870.6200b 90-Day Neuro. Screening Battery (rat)..........................

870.6300 Develop. Neuro .............................................................

no

no

yes

yes

no

-

-

yes

yes

-

870.7485 General Metabolism ......................................................

870.7600 Dermal Penetration........................................................

870.7800 Immunotoxicity..............................................................

yes

-

Yes

yes

-

no
Page 38 of 53

1.2 Toxicity Profiles

Table 2 Acute Toxicity Profile Acibenzolar-S-methyl 

Acibenzolar-S-methyl

Guideline No./

Study Type

MRID No. Results Toxicity 

Category

870.1100 Acute oral toxicity 44014214 LD50 >5000 mg/kg IV

870.1200 Acute dermal toxicity 44014216 LD50 >2000 mg/kg IV

870.1300 Acute inhalation toxicity 44014219 LC50 >5.022 mg/L IV

870.2400 Acute eye irritation 44014220 minimal III

870.2500 Acute dermal irritation 44014220 slight IV

870.2600 Skin sensitization 44014225 positive NA

Actigard 50WG

870.1100 Acute oral toxicity 44014215 LD50 >5000 mg/kg IV

870.1200 Acute dermal toxicity 44014217 LD50 >2000 mg/kg IV

870.1300 Acute inhalation toxicity 44014218 LC50 >2.79 mg/L IV

870.2400 Acute eye irritation 44014221 minimal III

870.2500 Acute dermal irritation 44014223 moderate III

870.2600 Skin sensitization 44014224 negative NA

Table 3 Subchronic, Chronic and Other Toxicity Profile for Acibenzolar-S-methyl 

Guideline No.

Study Type

MRID No. (year)

Classification

Dose Levels

Results

870.3100

90-day oral toxicity rodents 

(rat)

44014230 (1993)

Acceptable/Guideline

M : 0, 2.42, 24.6, 126, 516 

mg/kg/day;

F: 0, 2.64, 26.3, 131, 554 

mg/kg/day

NOAEL:126 mg/kg/day Males or M); 131 mg/kg/day (Females or 

F)

LOAEL:516 mg/kg/day (M); 554 mg/kg/day females based 

decreased body weight, reduced food intake and efficiency and 

increased liver and spleen weights

870.3150

90-day oral toxicity nonrodents (dog)

44014232 (1994)

Acceptable/Guideline

M & F: 0, 10, 50, 200 

mg/kg/day (capsules)

NOAEL:50 mg/kg/day (M & F)

LOAEL:200 mg/kg/day (F) based on regenerative hemolytic 

anemia evidenced by decreased erythroid parameters, pigmentation 

in the liver and spleen, splenic congestion, and by activation of 

medullary (bone marrow) and extramedullary (splenic) 

erythropoiesis.

870.3100

90-day oral toxicity rodents 

(mice)

44014228 (1993)

Acceptable/Guideline

0, 30.6, 152, and 624 

mg/kg/day for males, and 0, 

47.4, 220, and 803 mg/kg/day 

for females, respectively.

NOAEL: 30.6 mg/kg/day (M); 47.4 mg/kg/day (F)

LOAEL:152 mg/kg/day (M); 220 mg/kg/day females based 

decreased body weight and body weight gain, increased spleen 

weight and microscopic changes in the spleen
Page 39 of 53

Table 3 Subchronic, Chronic and Other Toxicity Profile for Acibenzolar-S-methyl 

Guideline No.

Study Type

MRID No. (year)

Classification

Dose Levels

Results

870.3200

21/28-day dermal toxicity (rat)

44014233 (1994)

Acceptable/guideline

M & F: 0, 10, 100, 1000 

mg/kg/day

NOAEL = 1000 mg/kg/day

LOAEL = not identified

870.3700a

Developmental Toxicity in 

rodents (rat)

44014236 (1994)

Acceptable/guideline

F: 0,10, 50, 200, 400 

mg/kg/day

Maternal NOAEL 200 mg/kg/day

Developmental NOAEL 50 mg/kg/day

Maternal LOAEL 400 mg/kg/day based on clinical signs of 

hemorrhagic perineal discharge

Developmental LOAEL 200 mg/kg/day based on developmental

malformations, anomalies, and skeletal variations

870.3700a

Developmental Toxicity in 

rodents (rat)

45089701 (1998)

Acceptable/guideline

of 0, 10, 75, 150, or 350

mg/kg/day

Maternal NOAEL 350 mg/kg/day

Developmental NOAEL 200 mg/kg/day

Maternal LOAEL – not established (>350)

Developmental LOAEL 350 mg/kg/day based on increased 

incidences of rudimentary and long lumbar ribs

870.3700b

Developmental Toxicity in 

non- rodents (rabbit)

44014237 (1994)

Acceptable/guideline

F: 0, 10, 50, 300, 600 

mg/kg/day

Maternal NOAEL = 50 mg/kg/day

LOAEL = 300 mg/kg/day based on mortality, clinical signs of 

toxicity, decreased maternal body weight and food consumption.

Developmental NOAEL = 300 mg/kg/day

LOAEL = 600 mg/kg/day based on a marginal increase in vertebral 

anomalies.

870.6300

Developmental Neurotoxicity 

Toxicity in rodents (rat)

46046401 (2002)

Acceptable/non-guideline

0/0, 8.2/15.5, 82.0/153.6, and 

326.2/607.8 mg/kg/day 

[gestation/lactation]. 

Maternal NOAEL 326.2 mg/kg/day

Developmental NOAEL 8.2 mg/kg/day

Maternal LOAEL Not Observed

Developmental LOAEL 82 based on changes in brain 

morphometrics in the cerebellum

870.3800

Reproduction and fertility 

effects in rats

4014241 (1995)

Acceptable/guideline

M & F: 0, 1-3, 11-31, 105-

288, 223-604 mg/kg/day

Parental/Systemic NOAEL = 11-31 mg/kg/day

LOAEL = 105-288 mg/kg/day based on increased weights and 

hemosiderosis of the spleen.

Reproductive NOAEL = 223-604 mg/kg/day

LOAEL > 223-604 mg/kg/day based on no effects.

Offspring NOAEL = 11-31 mg/kg/day

LOAEL = 105-288 mg/kg/day based on reduced pup body weight 

gains and lower pup body weights during lactation.
Page 40 of 53

Table 3 Subchronic, Chronic and Other Toxicity Profile for Acibenzolar-S-methyl 

Guideline No.

Study Type

MRID No. (year)

Classification

Dose Levels

Results

870.6200b 

Subchronic Neurotoxicity

45713601 (1997)

acceptable/nonguideline

pending submission of positive

control data for 

neuropathological and FOB 

assessments

0/0, 24/26, 126/143, and 

575/628 mg/kg/day [M/F], 

respectively

The study may be upgraded 

pending submission of 

acceptable positive control 

data.

NOAEL 126/143 mg/kg/day, M/F

LOAEL 575/628 mg/kg/day, M/F based on decreased body 

weights, body weight gains, and food consumption.

870.4100

Chronic toxicity in dogs

44014234 (1996)

Acceptable/guideline

M & F: 0, 5, 25, 200 

mg/kg/day (capsules)

NOAEL 25 mg/kg/day

LOAEL 200 mg/kg/day based on hematological effects, 

hemosiderosis of the liver and spleen, extraniedullary 

hematopoiesis in the spleen, and increases in liver weight.

870.4300

Chronic toxicity/ 

carcinogenicity in rodents 

(mice)

44014325 (1996)

Acceptable/guideline

M: 0, 1.14, 11.1, 237, 698 

mg/kg/day

F: 0, 1.14, 10.8, 234, 696 

mg/kg/day

NOAEL 11.1/10.8 mg/kg/day, M/F

LOAEL 237/234 mg/kg/day based on mild hemolytic anemia and 

related microscopic changes (hemosiderosis) in the spleen, liver, 

and bone marrow and extramedullary hematopoiesis in the spleen.

870.4200

Carcinogenicity study in rat

44014243 (1996)

Acceptable/guideline

M: 0, 0.77, 7.77, 96.9, 312 

mg/kg/day

F: 0, 0.90, 9.08, 111, 388 

mg/kg/day

NOAEL 96.9/111 (M/F)

LOAEL 312/388 / 191.0 mg/kg/d (M/F) based on decreased body 

weights, body weight gain and food efficiency, mild hemolytic 

anemia, and increased incidence of alveolar foam cells (females 

only).

870.5100

Bacterial reverse mutation 

assay (Ames test)

441014247 (1993)

Acceptable/guideline

312.5, 625, 1250, 2500, 5000 

g/plate

Negative with and without S-9 activation at 5000 g/plate and less.

870.5100

Bacterial reverse mutation 

assay (Ames test)

Test Material: CGA- 362020 

(isomer of acibenzolar-Smethyl)

44537025 (1998)

Acceptable/guideline

61.73 to 5000 g/plate (+S-9)

30-86 to 2500 g/plate (-S-9)

Positive in S. typhimurium strain TA1537 at 277.8 g/plate and 

higher in the absence of S-9. Negative with S-9 activation at 5000 

g/plate and less.
Page 41 of 53

Table 3 Subchronic, Chronic and Other Toxicity Profile for Acibenzolar-S-methyl 

Guideline No.

Study Type

MRID No. (year)

Classification

Dose Levels

Results

870.5100

Bacterial reverse mutation 

assay (Ames test)

Test Material: NOA- 419191 

(by-product of acibenzolar-Smethyl)

44537024 (1998)

Acceptable/guideline

312.5 to 5000 g/plate (± S-9)

Negative with or without S-9 activation at 5000 g/plate and less

870.5100

Bacterial reverse mutation 

assay (Ames test)

Test Material: CGA- 323060 

(plant metabolite of 

acibenzolar-S-methyl)

44537026 (1997)

Acceptable/guideline

312.5 to 5000 g/plate (± S-9)

Negative with or without S-9 activation at 5000 g/plate and less

870.5300

In vitro mammalian gene 

mutation assay 

44014246 (1993)

Acceptable/guideline

3.70 to 100 g/ml (-S-9), 

37.04 to 1000 g/ml (+S-9)

Negative with S-9 activation up to 1000g/ml. Negative without 

S-9 activation up to 100g/ml.

Compound tested to cytotoxic concentrations.

870.5375

In vitro mammalian 

chromosome aberration (CHO 

cells)

44014245 (1993)

Acceptable/guideline

7.5 to 60 g/ml (-S-9 and +S9)

Suggestive of clastogenicity in the absence of S-9 activation at 30 

and 60 g/mL at the 18-hour cell harvest time; effect observed only 

in the presence of cytotoxicity. Increase in polyploid cells at 30 

and 60 g/mL at the 42 hour harvest time both with and without S9. Evidence of cell cycle arresting activity at G2.

870.5395

Mammalian erythrocyte 

micronucleus test

44014244 (1993)

Acceptable/guideline

1000, 2000, 4000 mg/kg (oral 

gavage)

Negative at 16, 24, and 48, hour sacrifices.

870.5550

UDS in primary rat 

hepatocytes

44014248 (1993)

Acceptable/guideline

9.77 to 500 g/ml

Negative at 500 g/ml and less.

870.7485

Metabolism and 

pharmacokinetics

rats

44014250 (1995)

Acceptable/guideline

0.5, 100 mg/kg

Following oral treatment of rats, acibenzolar-S-methyl was rapidly 

and nearly completely (>90% of administered dose) absorbed from 

the gastrointestinal tract into the general circulation. The majority 

(88- 95%) of the administered dose was excreted in the urine 

within the first 48 hours. The major metabolite (79- 92%) in the 

urine was the carboxylic acid derivative of the parent.

870.7600

Dermal penetration

NA NA

Special studies:

28-Day dietary 

rats

44014227 (1992)

Acceptable/nonguideline

M: 0, 45.9, 403, 1070 

mg/kg/day; F: 0, 44.8, 376, 

1000 mg/kg/day

NOAEL = M: 403 mg/kg/day; F: 376 mg/kg/day

LOAEL = M: 1070 mg/kg/day; F: 1000 mg/kg/day based on 

decreased mean body weights, decreased liver weights, altered 

hematology parameters accompanied by increased spleen weights.
Page 42 of 53

Table 3 Subchronic, Chronic and Other Toxicity Profile for Acibenzolar-S-methyl 

Guideline No.

Study Type

MRID No. (year)

Classification

Dose Levels

Results

28-Day oral gavage

rats

44014229 (1993) 

Acceptable/nonguideline

0, 10, 100, 800 mg/kg/day 

NOAEL = 100 mg/kg/day

LOAEL = 800 mg/kg/day based on decreased body weights, and 

decreased hemoglobin-related parameters accompanied by 

hemosiderosis of the spleen, increased liver and spleen weights, and

decreased thymus weights.

28-Day oral capsule dogs 44014231 (1994) 

Acceptable/nonguideline

0, 50, 250, 500 mg/kg/day

NOAEL = 50 mg/kg/day

LOAEL = 250 mg/kg/day based on decreased body weight, 

decreased hemoglobin-related parameters, hepatic and splenic 

hemosiderosis.

90-Day Dietary 

mice

44014228 (1993)

Acceptable/nonguideline

M: 0, 30.6, 152, 624 

mg/kg/day; F: 0, 47.4, 220, 

803 mg/kg/day

NOAEL = M: 30.6 mg/kg/day; F: 47.4 mg/kg/day

LOAEL = M: 152 mg/kg/day; F: 220 mg/kg/day based on 

decreased mean body weights and body weight gain in males, 

increased spleen weights and splenic histopathology in both sexes. 

90-Day Dietary 

dog

44014232 (1994)

Acceptable/nonguideline

0, 10, 50, or 200 mg/kg/day

NOAEL = 50 mg/kg/day

LOAEL = 200 mg/kg/day in male and female dogs, based on 

regenerative hemolytic anemia evidenced by decreased erythroid 

parameters, pigmentation in the liver and spleen, splenic 

congestion, and by activation of medullary (bone marrow) and 

extramedullary (splenic) erythropoiesis.

90-Day Dietary 

rat

44014230 (1993)

Acceptable/nonguideline

males: 0,2.42, 24.6, 126, or 

516 mg/kg/day; females: 

0,2.64,26.3, 131, or 554 

mg/kg/day)

NOAEL = 126 mg/kg/day in males and 131 mg/kg/day

in females 

LOAEL = 516 mg/kg/day males and 554 mg/kg/day females based 

on decreased mean body weights, reduced food intake, reduced 

food efficiency, and increased liver and spleen weights with 

correlates for the liver and spleen of glycogen deposition and 

hemosiderosis, respectively. 

Special

Developmental toxicity 

rats

44014238 (1994)

Acceptable/nonguideline

300 mg/kg/day, GD 6-15, 6-7, 

8-9, 10-11, 12-13, or 14-15

Maternal and developmental NOAELS and LOAELS could not be

identified by this protocol. The most pronounced maternal and 

developmental toxicity occurred when dams were treated on GD 6-

15.

Special

Developmental toxicity

rats

44014239 (1994)

Acceptable/nonguideline

400 mg/kg/day, GD 6-7, 8-9, 

10-11, 12-13, or 14-15

Maternal and developmental NOAELS and LOAELS could not be 

identified by this protocol. The most pronounced maternal and 

developmental toxicity occurred when dams were treated on GD 6-

7 and 8-9.

Dermal developmental toxicity

rats

44014240 (1994)

Acceptable/nonguideline

0, 10, 100, 500 mg/kg/day, 

GD 6-15

Maternal NOAEL 500 mg/kg/day

LOAEL >500 mg/kg/day based on no effects.

Developmental NOAEL 500 mg/kg/day

LOAEL >500 mg/kg/day based on no effects.

Range-finding 

1-generation reproduction 

rats

44681301 (1993)

Acceptable/nonguideline

0, 199-209, 382-410, 700-728 

mg/kg/day

Parental/Systemic NOAEL = 209 mg/kg/day

LOAEL = 410 mg/kg/day based on decreased body weight gain and 

food consumption in females.

Reproductive NOAEL = 410 mg/kg/day

LOAEL = 728 mg/kg/day based on total resorptions in all dams.

Offspring NOAEL = 209 mg/kg/day

LOAEL = 410 mg/kg/day based on reduced pup body weight gains 

and lower pup body weights during lactation.
Page 43 of 53

2.0 Studies Reviewed for Ethical Conduct

The PHED Task Force, 1995. The Pesticide Handlers Exposure Database, Version 1.1. Task 

Force members Health Canada, U.S. Environmental Protection Agency, and the National 

Agricultural Chemicals Association, released February, 1995.

Agricultural Re-entry Task Force (ARTF) data base (SOP #3.1)
Page 44 of 53

3.0 ADDITIONAL TOXICOLOGY STUDIES 

870.3700 Developmental Toxicity

In a non-guideline developmental toxicity study (MRID 44014238), twelve presumed pregnant 

Tif:RAT f(SPF) (hybrids of RTT/1 x RII/2) rats per group were administered CGA 245704 

Technical (97.9%; Batch No. P.303011) in a 0.5% aqueous solution of sodium 

carboxymethylcellulose by gavage at a dose of 300 mg/kg/day. Groups 2-7 were administered 

test article on gestation days (GD) 6-15,6- 7, 8-9, 10-11, 12-13, or 14-15, respectively. Group 1 

consisted of twelve animals which served as controls and were treated with 0.5% sodium 

carboxymethylcellulose on GD 6-15. On GD 21, dams were sacrificed, subjected to gross 

necropsy, and all fetuses examined externally. Visceral and skeletal examinations were not 

performed. All animals survived until scheduled sacrifice on GD 21. Bloody, vaginal discharge 

was observed in 8/12 dams in Group 2, 3/12 dams in Group 3, 5/12 dams in Group 4, 4/12 dams 

in Group 5, and in 5/12 dams in Group 6. This finding was observed for one to four days starting 

on GD 13 and was not observed in controls or in animals in Group 7. No other treatment-related 

clinical signs of toxicity were observed. No statistically significant differences in absolute body

weights or body weight changes occurred at any time between the treated groups and the control 

group. Body weight gain by Group 2 was 80% of the control level during the treatment interval 

(GD 6- 16), with the greatest reduction in weight gain (77% of controls) during GD 11-16. Food 

consumption was not affected. There were no statistically significant differences between control 

and treatment groups for number of corpora lutea, number of implantation sites, live fetuses/dam, 

pre- and post-implantation loss, or fetal sex ratios. Fetal body weights from the Group 2 dams 

were significantly (p <0.01) less than the controls. Although not statistically significant, Group 2 

dams also had fewer live fetuses per litter (10.9 vs 14.8 for controls) and a greater post

implantation loss (30.1% vs 2.9% for controls) from early resorptions due to one dam with whole 

liner resorption (17/17) and 2 additional dams with 13/16 and 8/9 resorptions/number of 

implantation sites. The overall incidence rates for litters containing fetuses with major external 

malformations in Groups 1-7 were 0/12, 1/10, 0/10, 1/11, 0/11, 0/10, and 0/12, respectively. In 

one Group 2 litter, generalized edema was observed in 5/14 fetuses. In addition, two of the five 

also had a position anomaly of the hindlimb and one of the two also had gastroschisis. These five 

fetuses also had greatly reduced body weights. Generalized edema was also seen in one fetus 

from Group 4. Maternal and developmental toxicity NOAELs and LOAELs could not be 

identified by this protocol, which investigated the critical period of organogenesis. The most 

pronounced maternal and developmental toxicity occurred when dams were treated on GD 6-15, 

inclusive at a dose level of 300 mg/kg/day. This study is classified as Acceptable/non-guideline 

as a developmental toxicity study (83-3a) in rats.

In a non-guideline developmental toxicity study (MRID 44014239), eight presumed pregnant Tif: 

RAT f (SPF) (hybrids of RII/1 x RII2) rats per group were administered CGA 245704 Technical 

(97.9%; Batch No. P.303011) by gavage at a dose of 400 mg/kg/day. Groups 2-6 were 

administered test article on gestation days (GD) 6-7, 8-9, 10-11, 12-13, or 14-15, respectively. 

Group 1 consisted of eight animals which served as controls and were treated with 0.5% 

carboxymethylceliulose (vehicle) on GD 6-15. On GD 21, dams were sacrificed, subjected to 
Page 45 of 53

gross necropsy, and all fetuses examined externally. Visceral and skeletal examinations were not 

performed. One Group 2 dam was found dead on GD 20. Prior to death, this animal had bloody

perineal discharge and necropsy findings including mottled kidney and thymus. One Group 4 

dam delivered on GD 20 and was sacrificed. All other animals survived until scheduled sacrifice 

on GD 21. Bloody, perineal discharge was observed in 4/8 dams in Group 3. This finding was 

observed for three to four days starting on GD 16. The same 4 dams were later observed to have 

total lifter resorptions. No other treatment-related clinical signs of toxicity were observed. No 

statistically significant differences in body weights, body weight gains, or food consumption 

occurred at any time between the treated groups and the control group. There were no 

differences between the control group and Groups 4, 5, and 6 for number of corpora lutea, 

number of implantation sites, live fetuses/dam, pre- and post-implantation loss, fetal body

weights, or fetal sex ratios. Group 2 had a slightly greater number of early resorptions/dam (2.7 

vs 0.9 for controls) and an increased postimplantation loss (18.7% vs 5.4% for controls). The 

four Group 3 dams observed with bloody discharge had complete litter resorption resulting in 

increased postimplantation loss (53.4%). Group 3 also had an increase in early rcsorptions 

(8.0/dam vs 0.9/dam for controls) and decreased mean live fetuses/litter (8.5 vs 16.0 for 

controls). Another Group 3 dam had fused placentae between two fetuses. The overall incidence 

rates for liners containing fetuses with major external malformations in Groups 1-6 were 0/8, 0/6, 

0/4, 1/7, 0/8, and 0/8, respectively. One Group 4 fetus had cleft palate and another fetus from the 

same lifter had a kinked tail. No treatment-related external malformations /variations were 

observed in any fetus from any group. Maternal and developmental toxicity NOAELs and 

LOAELs could not be identified by this protocol, which investigated the critical period of 

organogenesis. Pronounced maternal and developmental toxicity occurred when dams were 

treated on GD 6-7 and 8-9 at a dose level of 400 mg/kg/day.

870.7600 Dermal Penetration

In a dermal developmental toxicity study (MRID 44014240), 24 pregnant Tif: RAIf (SPF) rats 

(Sprague-Dawley derived) per group were administered acibenzolar-S-methyl (97.9% a.i.) in 

aqueous carboxymethylcellulose (0.5% w/w) in 0.1% aqueous Polysorbate 80, by dermal 

application at doses of 0 (vehicle), 10, 100, or 500 mg/kg/day on gestation days (GD) 6-15, 

inclusive. Exposure duration was 6 hours per day. On GD 21, all dams were sacrificed and all 

fetuses were sexed, weighed, and examined for external malformations/variations, then 

sacrificed. Approximately one-half of each litter was placed in Bouin’s fixative for subsequent 

visceral examination and the remainder were prepared and stained for skeletal examination. All 

animals survived until scheduled sacrifice. No clinical signs of toxicity were observed at any

treatment level. Gestational body weights, body weight changes, and food consumption were not 

statistically significantly different for any treatment level throughout the gestational period.

Therefore, the maternal toxicity NOAEL is 500 mg/kg/day based on no adverse maternal effects 

at the highest administered dose. The maternal toxicity LOAEL was >500 mg/kg/day. No 

treatment-related effects were observed for gravid uterine weights, number of fetuses/litter, preand post-implantation losses, numbers of corpora lutea/dam, number of implantations/dam, 

resorptions/dam, fetal body weights, or fetal sex ratios. No biologically relevant statistically
Page 46 of 53

significant differences in the incidence rates of any external, visceral, or skeletal malformations/

anomalies/variations were observed in the treated litters as compared to the controls. There were 

statistically significantly decreased incidences of absent ossification of the proximal phalanx of 

anterior digit-2 in all treatment groups and poor ossification of the proximal phalanx of posterior 

digit-2 in the 500 mg/kg/day treatment group as compared to the control group. However, these 

decreases were not considered to be biologically significant. Therefore, the developmental 

toxicity NOAEL is 500 mgfkglday based on no adverse developmental effects at the highest dose 

administered. The developmental toxicity LOAEL was >500 mg/kg/day.

In a 28- day repeated dose dermal toxicity study (MRID 44014233), groups of 5 females Tif: 

RAIf (SPF) albino rats were treated with acibenzolar-S-methyl technical in 0.5% (w/v) 

carboxymethyl cellulose/0.1% (w/v) aqueous polysobate 80 at does of 0, 1, 10, 100 or 1000 

mg/kg/day. Animals were treated by dermal occlusion for 6 hours/day, 5 days/week for 4 weeks. 

No animals died during the study. There were no treatment- related clinical signs, dermal 

effects, effects on body weight, food consumption, hematology, clinical chemistry, or organ 

weight. No gross or microscopic pathology were noted at necropsy. The systemic and dermal 

NOAEL is the limit dose of 1000 mg/kg/day. A dermal and systemic LOAEL were not 

identified. 

870.3800 Reproduction

In a 1-generation range-finding reproduction study in rats (Nonguideline study, MRID 44014241)

CGA 245704 Technical (97.9% a.i.; Batch No. P.303011) was administered to groups of 15 male 

and 15 female Tif: RAT f (SPF), hybrids of RTTI 1 x P11/2 (Sprague-Dawley derived) rats at 

dietary concentrations of 0, 2000, 4000, or 8000 ppm for one generation (MRID 44681301). In 

this range- finding study, F0 adults were administered test or control diet for two weeks prior to 

mating. Premating doses were 199.4, 382.0, and 700.1 mg/kg/day, respectively, for F0 males and 

208.7, 409.9, and 727.8 mg/kg/day, respectively, for F0 females. Males were terminated at the 

end of mating and females were terminated at weaning of their pups. All offspring, except five 

litters per dose group, were necropsied at weaning. After weaning, five litters per dose group 

were retained on treatment for an additional three weeks and then necropsied. The only clinical 

sign of toxicity in the parental animals was perineal hemorrhage during late gestation in five 

high-dose females. Gross necropsy was unremarkable. Absolute body weights, body weight 

gains, and food consumption values for the low- and mid-dose males and low-dose females were 

similar to the controls throughout the study. High-dose males had significantly (p > 0.01; 88-91% 

of control) lower body weights than the controls beginning on day 8 and continuing until study

termination. Overall weight gain by the high-dose males was 69% of the control level. Body

weights and body weight gains of the high-dose females were significantly (p > 0.01; body

weights 88-90% of controls) Tess than the controls during the premating interval. Overall body

weight gain by the high- dose group was only 30% of the control group level. Mid-dose females 

had significantly (p > 0.05) lower body weight gains than the controls during days 1-8. Reduced 

body weight gains in the high- dose males and females and mid-dose females correlated with 

significantly (p > 0.05 or 0.01) reduced food consumption by these treated groups during study

days 1-8. Lower body weights, body weight gains, and food consumption continued for the mid-
Page 47 of 53

and high-dose females during gestation and lactation. Body weights of the high-dose group were 

significantly (p > 0.05 or 0.01) lower than the controls throughout gestation with overall weight 

gain by the high-dose females during gestation 27% (p > 0.01) of the control group level. Middose females had significantly (p > 0.05 or 0.01) lower body weights than the controls on GD 21 

and on lactation days 7, 14, and 21. Weight gains by the mid-dose group during gestation and 

lactation were 92% and 83%, respectively of the control group levels. Food consumption by the 

high-dose group was significantly (p > 0.05 or 0.01) less than the controls throughout gestation. 

Food consumption by the mid-dose group was significantly (p > 0.01) less than the controls 

throughout lactation. Therefore, the LOAEL for parental toxicity is 4000 ppm based on reduced 

food consumption and lower body weight gains in F0 females. The parental toxicity NOAEL is 

2000 ppm. Mating and fertility indices, mean precoital interval, mean gestation length, and mean 

numbers of corpora lutea and implantation sites per dam were similar between the treated and 

control groups. Mating and fertility indices for the high-dose group were similar to the control 

group, but no live lifters were produced by the high-dose group (i.e. all pregnancies were lost). 

Live births and pup survival were similar between the low- and mid-dose groups and the control 

group. Therefore, the LOAEL for reproductive toxicity is 8000 ppm based on total resorptions in 

all dams. The reproductive toxicity NOAEL is 4000 ppm. No treatment-related clinical signs of 

toxicity were observed in the pups during lactation. Absolute body weights of pups in the lowdose group were similar to the controls throughout lactation. Body weights of the mid-dose pups 

were significantly (p > 0.05 or 0.01; 76-89% of controls) less than the controls beginning on 

lactation day 7 and continuing throughout lactation and postweaning. The lower body weights of 

the mid-dose pups were a result of significantly (p > 0.05 or 0.01; 69-89% of controls) lower 

body weight gains from postnatal day 4 through postnatal day 28. Recovery of body weight gains 

occurred during the postweaning intervals of days 28-35 and 35-42. Therefore, the LOAEL for 

developmental toxicity is 4000 ppm based on reduced pup body weight gains and lower pup body

weights during lactation and early postweaning. The developmental toxicity NOAEL is 2000 

ppm.

870.6200b Subchronic Neurotoxicity

In a subchronic neurotoxicity study (MRID 45713601), CGA-245704 (Acibenzolar, 97.9% a.i., 

Batch No. P.303011) was administered in the diet to 10 Sprague-Dawley derived rats/sex/group

at dose levels of 0, 400, 2000, or 8000 ppm (equivalent to 0/0, 24/26, 126/143, and 575/628 

mg/kg/day [M/F], respectively) for at least 90 days. Neurobehavioral assessment (functional 

observational battery [FOB] and motor activity testing) was performed using all rats at predosing and Weeks 4, 8, and 13. At study termination, 5 rats/sex/group were anesthetized and 

perfused in situ for neuropathological examination. The tissues from the perfused animals in the 

control and 8000 ppm groups were subjected to histopathological evaluation of brain and 

peripheral nervous system tissues. Positive control data were not provided. No compoundrelated effects were observed in mortality, clinical signs of toxicity, FOB, motor activity, or gross 

or neuropathology. At 8000 ppm, body weights were generally decreased throughout the study in 

the males (decr 11-14%, not statistically significant) and females (decr 8-13%, attaining 

statistical significance at Weeks 2-5, 7 and 8, and 11-13). Also at this dose, cumulative body
Page 48 of 53

weight gains were decreased throughout the study in the males (decr 19-35%, attaining statistical 

significance at Weeks 2-4 and 6-9), and in the females (decr 24-40%). A decreasing trend 

(p<0.01) in body weight and body weight gain was also generally noted in both sexes at this 

dose. These decreases in body weight gain corresponded with decreases in food consumption 

(g/animal/day) which was sporadically decreased in the 8000 ppm males (decr 9-21% at Weeks 

1-3, 5-7, and 11, but only attaining statistical significance during Week 1), and females (decr 14-

18%, p<0.01 at Weeks 1 and 3). A decreasing trend (p<0.01) in food consumption was also 

generally noted in the males at 8000 ppm during the weeks reported above. No neurological 

effects were observed at any dose in either sex. The LOAEL was 8000 ppm (equivalent to 

575/628 mg/kg/day, M/F) based on decreased body weights, body weight gains, and food 

consumption. The NOAEL is 2000 ppm (equivalent to 126/143 mg/kg/day, M/F). This study is 

classified as acceptable/nonguideline pending submission of positive control data for 

neuropathological and FOB assessments and does not satisfy the guideline requirement (OPPTS 

870.6200b) for a subchronic neurotoxicity study in rats. The study may be upgraded pending 

submission of acceptable positive control data.

870.5100, 870-5300, 870.5375, 870.5900 Mutagenicity 

Five acceptable mutagenicity studies on technical grade acibenzolar-S-methyl are available:

1. Reverse gene mutation, S. typhimuriumlE. Coli (MRID 44014247)

2. Forward gene mutation, Chinese hamster V79 lung cells in culture/HGPRT locus (MRID

44014246)

3. Chromosome aberration, Chinese hamster ovary (CHO) cells in culture (MRID 44014245)

4. Unscheduled DNA synthesis assay, primary rat hepatocytes in culture (MRID 44014248)

5. In vivo cytogenetics, micronucleus assay in mice (MRID 44014244)

Results in all five studies were negative for genotoxicity. The five studies on the technical 

grade product satisf’ the new revised mutagenicity guideline requirements for a new chemical 

(published in 1991). 

Three additional acceptable mutagenicity studies on a) an isomer (CGA-362020) of acibenzolar 

S-methyl, b) a by-product (NOA 419191) of acibenzolar-S-methyl, and c) a plain metabolite 

(CGA-323060) of acibenzolar-S-methyl are also available.

1. Reverse gene mutation, S. typhimuriumlE. Coli; Test Material: CGA-362020 (MRID

44537025). This study was POSITIVE for evidence of induced mutant colonies over 

background in S. typhimurium strain TA1537 at concentrations of 277.8 and higher in the 

absence of 59-mix.

2. Reverse gene mutation, S. typhimuriumlE. Coli; Test Material: NOA 419191 (MRID

44537024). This study was negative.

3. Reverse gene mutation, S. typhimuriumfE. Coli; Test Material: CGA-323060 (MRlD

44537026). This study was negative
Page 49 of 53

CGA-362020, an isomer of acibenzolar-S-methyl, is a low level impurity arising from a new 

production process for acibenzolar-S-methyl, which has not yet been submitted to the Agency. 

Trace levels of this isomer (<0.1%) were found in some batches of technical grade acibenzolar-Sniethyl produced via the new production process. See the 6(a)(2) letter from Novartis, dated 

3/16/98, reporting the findings in this mutagenicity study and the above information regarding 

the formation of this isomer in the new production process. Presumably, the same isomer does 

not occur in the old production process which produced the test material (lot/batch # P.303011) 

that was used for virtually all the toxicity testing on acibenzolar-S-methyl up to this point in time.
Page 50 of 53

4.0 TOXICOLOGY STUDY REFERENCES

44014227 Bachmann, M. (1992) CGA-245704 Technical: 28-Day Range Finding Study in Rats: 

(Administration in Food): (Final Report): Lab Project Number: 923060. Unpublished study

prepared by Ciba-Geigy Ltd. 221 p. 

44014228 Fankhauser, H. (1993) CGA-245704 Technical: 3-Month Range Finding Toxicity Study in 

Mice: (Administration in Food): (Final Report): Lab Project Number: 923081: 331018. 

Unpublished study prepared by Ciba-Geigy Ltd. 214 p. 

44014229 Fankhauser, H. (1993) CGA-245704 Technical: 28-Day Oral Cumulative Toxicity Study in 

Rats (Gavage): (Final Report): Lab Project Number: 923137: 349064. Unpublished study

prepared by Ciba-Geigy Ltd. 276 p. 

44014230 Bachmann, M. (1993) CGA-245704 Technical: 3-Month Oral Toxicity Study in Rats: 

(Administration in Food): (Final Report): Lab Project Number: 923082: 338433. Unpublished 

study prepared by Ciba-Geigy Ltd. 404 p. 

44014231 Altmann, B. (1994) CGA-245704 Technical: 28-Day Range Finding Toxicity Study in Beagle 

Dogs: (Final Report): Lab Project Number: 923130. Unpublished study prepared by CibaGeigy Ltd. 238 p. 

44014232 Altmann, B. (1994) CGA-245704 Technical: 90-Day Subchronic Oral Toxicity Study in 

Beagle Dogs: (Final Report): Lab Project Number: 923138. Unpublished study prepared by

Ciba-Geigy Ltd. 417 p. 

44014233 Hagemann, C. (1994) CGA-245704 Technical: 28-Day Repeated Dose Dermal Toxicity Study

in the Rat: (Final Report): Lab Project Number: 923135: 353867. Unpublished study prepared 

by Ciba-Geigy Ltd. 248 p. 

45713601 Classen, W. (1997) 90-Day Subchronic Neurotoxicity Study in Rats: CGA-245704 Technical: 

Final Report: Lab Project Number: 963028: 568-96: CH-4002. Unpublished study prepared by

Novartis Crop Protection, Inc. 259 p. {OPPTS 870.6200} 

44014234 Altmann, B. (1996) CGA-245704 Technical: 12-Month Chronic Oral Toxicity Study in Beagle 

Dogs: (Final Report): Lab Project Number: 923149. Unpublished study prepared by CibaGeigy Ltd. 574 p. 

44014243 Fankhauser, H. (1996) CGA-245704 Technical: 24-Month Carcinogenicity and Chronic 

Toxicity Study in Rats: (Final Report): Lab Project Number: 923151. Unpublished study

prepared by Ciba-Geigy Ltd. 1587 p. 

44014235 Fankhauser, H. (1996) CGA-245704 Technical: 18-Month Oncogenicity Study in Mice: (Final 

Report): Lab Project Number: 923150. Unpublished study prepared by Ciba-Geigy Ltd. 1024 

p. 

44014243 Fankhauser, H. (1996) CGA-245704 Technical: 24-Month Carcinogenicity and Chronic 

Toxicity Study in Rats: (Final Report): Lab Project Number: 923151. Unpublished study

prepared by Ciba-Geigy Ltd. 1587 p. 

44014236 Marty, J. (1994) CGA-245704 Technical: Rat Oral Teratogenicity: (Final Report): Lab Project 

Number: 923139: 349097. Unpublished study prepared by Ciba-Geigy Ltd. 407 p. 

44014237 Marty, J. (1994) CGA-245704 Technical: Rabbit Oral Teratogenicity: (Final Report): Lab 
Page 51 of 53

Project Number: 923140: 360382. Unpublished study prepared by Ciba-Geigy Ltd. 266 p. 

44014238 Khalil, S. (1994) CGA-245704 Technical: Range Finding Rat Oral Teratogenicity: (NonStandard Study): (Final Report): Lab Project Number: 943067. Unpublished study prepared by

Ciba-Geigy Ltd. 135 p. 

44014239 Khalil, S. (1994) CGA-245704 Technical: Range Finding Rat Oral Teratogenicity: (NonStandard Study): (Final Report): Lab Project Number: 943004. Unpublished study prepared by

Ciba-Geigy Ltd. 118 p. 

44014240 Khalil, S. (1994) CGA-245704 Technical: Rat Dermal Teratogenicity: (Final Report): Lab 

Project Number: 943001: 370440. Unpublished study prepared by Ciba-Geigy Ltd. 381 p. 

45089701 Miyamoto, M. (1998) Teratology Study of Acibenzolar-S-methyl in Rats: Final Report: Lab 

Project Number: AN98025: 1197-98. Unpublished study prepared by Ina Research Inc. 131 p.

{OPPTS 870.3700} 

44014241 Khalil, S. (1995) CGA-245704 Technical: Two-Generation Reproduction Study in Rats: (Final 

Report): Lab Project Number: 923152. Unpublished study prepared by Ciba-Geigy Ltd. 1628 

p. 

44681301 Marty, J. (1993) CGA-245704 Technical: Rangefinding Rat Dietary Reproduction Study: Lab 

Project Number: 923146: 634-93. Unpublished study prepared by Novartis Crop Protection, 

Inc. 65 p. 

44014244 Hertner, T. (1993) CGA-245704 Technical: Micronucleus Test: Mouse (OECD Conform) in 

vivo Study: Lab Project Number: 923143. Unpublished study prepared by Ciba-Geigy Ltd. 40 

p. 

44014245 Hertner, T. (1993) CGA-245704 Technical: Cytogenetic Test on Chinese Hamster Cells in 

vitro (EC-Conform): Lab Project Number: 923142. Unpublished study prepared by Ciba-Geigy

Ltd. 45 p. 

44014246 Geleick, D. (1993) CGA-245704 Technical: Gene Mutation Test with Chinese Hamster Cells 

V79 in vitro: Lab Project Number: 923141. Unpublished study prepared by Ciba-Geigy Ltd. 53 

p. 

44014247 Hertner, T. (1993) CGA-245704 Technical: Salmonella and Escerichia/Liver Microsome Test: 

Gene Mutation Test: Lab Project Number: 923145. Unpublished study prepared by Ciba-Geigy

Ltd. 67 p. 

44014248 Hertner, T. (1993) CGA-245704 Technical: Autoradiographic DNA Repair Test on Rat 

Hepatocytes (OECD Conform) in vitro: Lab Project Number: 923144. Unpublished study

prepared by Ciba-Geigy Ltd. 86 p. 

44537024 Deparade, E. (1998) Salmonella and Escherichia/Mammalian-Microsome Mutagenicity Test: 

NOA 419191 Technical: Lab Project Number: 973097: 324-98: A98013. Unpublished study

prepared by Novartis Crop Protection, AG. 75 p. 

44537025 Deparade, E. (1998) Salmonella and Escherichia/Mammalian-Microsome Mutagenicity Test: 

CGA-362020 Technical: Lab Project Number: 973079: 325-98. Unpublished study prepared by

Novartis Crop Protection, AG. 74 p. 

44537026 Ogorek, B. (1997) Salmonella and Escherichia/Mammalian-Microsome Mutagenicity Test: 

CGA-323060 Technical: Lab Project Number: 963125: 761-97: A960043. Unpublished study
Page 52 of 53

prepared by Novartis Crop Protection, AG. 74 p. 

45434101 Deparade, E. (1998) Salmonella and Esherichia/Mammalian-Microsome Mutagenicity Test: 

CGA-245704: Final Report: Lab Project Number: 983053: 1240-98. Unpublished study

prepared by Novartis CropProtection AG. 71 p. {OPPTS 870.5100} 

44014250 Molitor, E. (1995) The Metabolism of (U-(carbon 14))Phenyl CGA-245704 in the Rat: Lab 

Project Number: 13/94: 016AM03. Unpublished study prepared by Ciba-Geigy Ltd. 197 p. 
Page 53 of 53

5.0 CHEMICAL NAMES AND STRUCTURES OF METABOLITES

N

N

S

O SCH3

Acibenzolar N

N

S

COOH

CGA 210007

N

N

S

COOH

HO

CGA 324041

N

N

S

COOH

OH

CGA 323060

S

COOH

O

CH3

CGA 379019

CGA 379789

S

COOH

O

CH3

O

CGA 379018

S

COOH

CH3

TRR, % ppm 

Lettuce 0.6 0.006

Tomato

 Fruit 7.3 0.023

 Leaves 1.5 0.011

Wheat

 Forage 2.4 0.007

 Straw 1.3 0.004

 Grain 4.8 <0.001

Rice

 Straw 0.5 0.009

TRR, % ppm 

Lettuce 20.1 0.204

Tomato

 Fruit 4.8 0.015

 Leaves 6.1 0.044

Wheat

 Forage 2.4 0.007

 Straw 1.3 0.004

 Grain 4.8 <0.001

TRR, % ppm 

Lettuce 25.1 0.255

Tomato

 Fruit 65.2 0.203

 Leaves 19.2 0.138

Wheat

 Forage 57.9 0.168

 Straw 43.5 0.149

 Grain 39.3 0.001

Rice

 Grain 5.6 0.005

 Hulls 16.8 0.027

 Straw 56.2 1.120

TRR, % ppm 

Lettuce 16.9 0.171

Tomato

 Fruit 0.8 0.002

 Leaves ND ND

Wheat ND ND

Rice ND ND

TRR, % ppm 

Rice

 Grain 18.8 0.016

 Hulls 7.9 0.013

 Straw 8.8 0.175

also found in paddy water

TRR, % ppm 

Rice

 Grain 3.6 0.003

 Straw 0.1 0.002

also found in paddy water

TRR, % ppm 

Rice

 Straw 0.7 0.014

also found in paddy water