Docket ID#: EPA-HQ-OPP-2009-0814

COMPANY NOTICE OF FILING 

EPA Registration Division contact: Sidney Jackson (703) 305-6224 

Interregional Research Project No. 4 (IR-4) in cooperation with Syngenta Crop 

Protection

PP9E7607

EPA has received a pesticide petition PP9E7607 from the Interregional 

Research Project No. 4 (IR-4), IR-4 Project Headquarters, Rutgers, The State 

University of NJ, 500 College Road east, Suite 201 W, Princeton, NJ 08540, in 

cooperation with Syngenta Crop Protection, Inc., 410 Swing Rd., Greensboro, NC 

27419, proposing, pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic 

Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 180.368 by establishing a 

tolerance for combined residues (free and bound) of S-metolachlor, S 2-chloro-N-(2-

ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, its R-enantiomer, 

and its metabolites, determined as the derivatives, 2-[(2-ethyl-6-

methylphenyl)amino]-1-propanol and 4-(2-ethyl-6-methylphenyl)-2-hydroxy-5-

methyl-3-morpholinone, each expressed as the parent compound in or on the raw 

agricultural commodities: carrot, cucumber, okra, sesame seed, sweet sorghum, leafy 

brassica greens subgroup 5B, turnip greens, melon crop subgroup 9A, caneberry 

crop subgroup 13-07A, blueberry, lowbush, bushberry crop subgroup 13-07B, 

onion, bulb subgroup 3-07A, and onion, green crop subgroup 3-07B at 0.3, 0.1, 0.1, 

0.1, 0.1, 1.2, 1.2, 0.08, 0.08, 1.4, 0.15, 0.1, and 2.0 parts per million (ppm), respectively. 

EPA has determined that the petition contains data or information regarding the elements 

set forth in section 408 (d)(2) of FDDCA; however, EPA has not fully evaluated the 

sufficiency of the submitted data at this time or whether the data supports granting of the 

petition. Additional data may be needed before EPA rules on the petition.

A. Residue Chemistry

1. Plant metabolism. The qualitative nature of S-metolachlor residues in 

plants is adequately understood based upon available EPA approved corn, potato, 

and soybean metabolism studies. The metabolism of S-metolachlor involves 

conjugation with glutathione, breakage of this bond to form the mercaptan, 

conjugation of the mercaptan with glucuronic acid, hydrolysis of the methyl ether, 

and conjugation of the resultant alcohol with a neutral sugar. EPA has determined 

that residues of concern in plants include parent and metabolites determined as the 

derivatives CGA-37913 and CGA-49751.
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2. Analytical method. The Pesticide Analytical Manual (PAM) Vol. II, 

Pesticide Regulation Section 180.368 lists a GC/NPD method (Method 1) for 

determining residues in / on plants and a GC/MSD method for determining residues 

in livestock commodities. These methods determine residues of S-metolachlor and 

its metabolites as either CGA-37913 or CGA-49751 following acid hydrolysis. The 

limit of quantitation (LOQ) for the method is 0.03 ppm for CGA-37913 and 0.05 

ppm for CGA-49751. Syngenta has also developed a chiral specific analytical 

method to allow for the determination of residues that are specific to S-metolachlor. 

It is this chiral specific method that Syngenta and IR-4 proposes for future use as 

the analytical enforcement method in support of these requested tolerances. 

Syngenta No. 1848-01 was used in several of the studies in this petition to analyze 

agricultural commodities. The latter chiral specific method is the same as the 

updated tolerance enforcement method, except that chiral chromatography and 

LC/MS/MS are used to separate and quantitate the hydrolysis products SYN506357 

(s-configured enantiomer of CGA-37913) and SYN508500 (s-configured enantiomer 

of CGA-49751).

3. Magnitude of residues. Carrot: Fourteen magnitude of residue trials were 

conducted under the direction of IR-4 in NAFTA Region 1A (PEI; one trial), Region 

4 (FL and GA, one trial each), Region 5 (ON, two trials; QC, two trials; & WI, one 

trial), Region 6 (TX, one trial), Region 9 (CA, four trials) and Region 10 (WA, one 

trial). Foliar applications at 0.63 or 1.26 lbs ai/A were made postemergence at the 3-

5 leaf growth stage during 2004. Carrots were harvested at normal maturity 

ranging from 26-121 days after application. Total maximum residues in carrots 

were <0.28 ppm when treated with the highest application rate. 

Cucumber: Fifteen magnitude of residue trials were conducted under the direction 

of IR-4 in Region 3 (MD, one trial), Region 4 (TN, NC, FL, and GA, one trial each), 

Region 5 (ON, three trials; QC, two trials), Region 6 (NM & TS, one trial each), and 

Region 10 (BC, three trials). Foliar applications at 0.63 or 1.2 lbs ai/A were made 

postemergence at the 3-5 leaf growth stage during 2005. Cucumbers were harvested 

at normal maturity ranging from 32-52 days after application. Total maximum 

residues in cucumbers were <0.1 ppm when treated with the highest application 

rate.

Okra: A tolerance is being proposed at 0.1 ppm based upon already existing 

tolerance in Vegetable, Fruiting Crop Group 8 (except Tabasco pepper).

Sesame seed: Four magnitude of residue trials were conducted under the direction 

of IR-4 in NAFTA Region 6 (TX, four trials) on sesame. Applications were made as 

a preemergence broadcast application prior to crop emergence. Sesame seed were 

harvested at normal maturity ranging from 101-128 days after application. In 

addition, at one site a bulk sample was collected for processing. Total maximum 

residues in sesame seed from preemergence applications was <0.10 ppm. Total 

maximum residues from processed sesame seed (processed fractions were oil and 

meal) was <0.1 ppm indicating that there is no potential for concentration of 

residues in the processed commodities of sesame seed.

Sweet sorghum: Three magnitude of residue trials were conducted under the 

direction of IR-4 in NAFTA Region 4 (TN, two trials) and Region 6 (TX, one trial) 
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on sweet sorghum. Applications were made preemergence broadcast prior to crop 

emergence at 1.0 or 1.67 lbs ai/A or early postemergence at 0.64 or 1.27 lbs ai/A. 

Sweet sorghum was harvested at normal maturity ranging from 87-108 days after 

application. In addition, at one site (TX) a bulk sample from the control and high 

treatment rate plot was collected for processing into syrup. Total maximum residues 

in sweet sorghum from preemergence applications or postemergence applications 

was <0.1 ppm. Total maximum residues from processed sweet sorghum (molasses) 

was <0.15 ppm indicating that there is no potential for concentration of residues in 

the processed commodities of sweet sorghum.

Leafy Brassica Greens Crop Group 5B

Mustard Greens: Twelve magnitude of residue trials were conducted under the 

direction of IR-4 in NAFTA Region 2 (NC-two trials; NJ-one trial), Region 3 (FLone trial) Region 4 (TN-one trial), Region 5 (MI-one trial, ON-two trials), Region 6 

(TX, one trial), Region 10 (CA, two trials) and Region 12 (BC, one trial) on mustard 

greens during 2004-2005. Applications were made at 0.63 or 1.26 lbs ai/A 

preemergence or early postemergence as a broadcast application. Harvests were 

made at normal maturity ranging from 20-40 days after the early postemergence 

applications and 33-62 days after the preemergence applications. Total maximum 

residues in mustard greens ranged from 0.17-0.18 ppm at the low application rate 

and 0.43-0.67 ppm at the high application rate. This data supports the leafy 

brassica greens, subgroup 5-B and turnip greens proposed tolerances.

Turnip Greens: A tolerance is being proposed at 1.2 ppm based on proposed 

tolerance for Leafy Brassica Greens Crop Group 5B. 

Melon Crop Group 9A:

Cantaloupe: Eleven magnitude of residue trials were conducted under the direction 

of IR-4 in NAFTA Region 2 (NJ; one trial), Region 4 (NC, one trial) Region 5 (MI, 

ON; one trial each), Region 5B (ON, one trial), Region 8 (TX, two trials), Region 10 

(CA, three trials; NM, one trial) on cantaloupe during 2003. Applications were 

made at 2 lbs ai/A 1] preemergence as a broadcast application to the row middles 

after laying plastic mulch or 2) preemergence or before transplanting prior to the 

laying the plastic mulch. Fruit were harvested at normal maturity ranging from 

61-112 days after application. Total maximum residues in cantaloupe were <0.08 

ppm regardless of the application method or timing. 

Caneberry Crop Group 13-07A: Five magnitude of residue trials were conducted 

under the direction of IR-4 in NAFTA Region 1 (PA, one trial, red raspberry), 

Region 5 (MI, one trial, red raspberry), and Region 12 (OR, three trials, one 

blackberry and two red raspberry) on cane berries. A single post-directed banded 

application was made preemergence to the weeds and fruit were harvested at 

normal maturity 28-30 days after application. Total maximum residues in cane 

berries from a single banded application was <0.08 ppm. 

Bushberry Crop Group 13-07B: Eleven magnitude of residue trials were conducted 

under the direction of IR-4 in NAFTA Region 1, 2, 5, 10, 12 and PMRA Regions 5b 

and 12 on blueberry. In highbush blueberry, a single post-directed banded 

application was made preemergence to the weeds and fruit were harvested at 

normal maturity 27-33 days after application. In lowbush blueberry, a single 

broadcast application was made preemergence to the weeds and fruit were 
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harvested at normal maturity 27-33 days after application. Total maximum residues 

in bushberry from a single application was <0.04 ppm.

Onion, bulb Crop Subgroup 3-07A and Onion, dry Crop Subgroup 3-07B:

requested tolerances are based on existing tolerances for s-metolachlor on onion, 

dry bulb (0.1 ppm) and onion, green (2.0 ppm).

B. Toxicological Profile

1. Acute toxicity. The data base for acute toxicity for S-metolachlor is 

complete. S-metolachlor is moderately acutely toxic (Toxicity Category III) by the 

oral and dermal route and relatively non-toxic (Toxicity category IV) by the 

inhalation route. It causes slight eye irritation (Toxicity Category III) and is nonirritating dermally (Toxicity Category IV); the active ingredient was found to be 

positive in a dermal sensitization test but this effect is mitigated in end-use product 

formulations.

2. Genotoxicty. The data base for S-metolachlor has been deemed to be 

adequate by EPA. Gene mutation studies (Guideline 870.5100), micronucleus 

(Guideline 870.5395), and unscheduled DNA synthesis (Guideline 870.5550) studies 

have recently been reviewed and approved by EPA. There is no evidence of a 

mutagenic or cytogentic effect in vivo or in vitro with S-metolachlor.

3. Reproductive and developmental toxicity. The data base for developmental 

and reproductive toxicity for S-metolachlor are considered complete according to 

EPA reviews. The prenatal developmental studies in the rat and rabbit with Smetolachlor revealed no evidence of a qualitative or quantitative susceptibility in 

fetal animals. No significant developmental toxicity was observed in most studies 

even at the highest does tested. In a two-generation reproduction study, there was 

no evidence of parental or reproductive toxicity at the highest dose tested (80 

mg/kg/day). The results indicate that S-metolachlor is not embryotoxic or 

teratogenic in either species at maternally toxic doses.

4. Subchronic toxicity. In a 90-day dietary study in rats with S-metolachlor, no 

effects were observed in male or females at 208 and 236 mg/kg/day, respectively. In 

another 90-day dietary study in rats, decreased body weight, reduced food 

consumption and food efficiency in both sexes and increased kidney weight in males 

at 150 mg/kg/day; the NOAEL was 15 mg/kg/day. A 90-day dog study with Smetolachlor in dogs has been accepted by EPA; no effects were observed in males 

and females at 62 mg/kg/day and 74 mg/kg/day, respectively, the highest doses 

tested.

5. Chronic toxicity. The data base that supports S-metolachlor is considered 

adequate by EPA. A combined chronic toxicity / carcinogenic study in the rat 

satisfies the requirements for both the chronic toxicity and carcinogenicity studies. 

No significant chronic toxicity was found in either rats or dogs. In the rat, a 
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decrease in body weight was observed at the highest dose tested. In the chronic dog 

study that supports S-metolachlor, the only adverse effect was decreased body 

weight gain in females at 33 mg/kg/day; the NOAEL was 10 mg/kg/day.

6. Animal metabolism. The data base for S-metolachlor is considered to be 

complete. In animals, S-metolachlor is extensively absorbed, rapidly metabolized 

and almost totally eliminated in the excreta of rats, goats, and poultry. Metabolism 

in animals proceeds through common Phase 1 intermediates and glutathione 

conjugation.

7. Metabolite toxicology. The metabolism of S-metolachlor has been well 

characterized in standard FIFRA metabolism studies. S-metolachlor does not 

readily undergo dealkylation to form an aniline or quinone imine as has been 

reported for other members of the chloroacetanilide class of chemicals. Therefore, 

as EPA has agreed, it is not appropriate to include S-metolachlor with the group of 

chloroacetanilides that readily undergo dealkylation, producing a common toxic 

metabolite (quinone imine). EPA has recently reviewed new toxicology data 

submitted by Syngenta demonstrating that the S-metolachlor metabolites ethane 

sulfonic acid (CGA 354743) and oxanilic acid (CGA 51202) are not absorbed by 

mammalian systems and / or have a significantly lower level of mammalian toxicity 

when compared to parent.

8. Endocrine disruption. S-Metolachlor does not belong to a class of chemicals 

known or suspected of having adverse effects on the endocrine system. There is no 

evidence that S-metolachlor has any effect on endocrine function in developmental 

or reproduction studies. Furthermore, histological investigation of endocrine 

organs in the chronic dog, rat and mouse studies did not indicate that the endocrine 

system is targeted by S-metolachlor, even at maximally tolerated doses administered 

for a lifetime. There is no evidence that S-metolachlor bioaccumulates in the 

environment.

C. Aggregate Exposure

1. Dietary exposure. Acute (Tier I) and chronic (Tier III/IV) dietary exposure 

evaluations were made for S-metolachlor using the Dietary Exposure Evaluation 

Model software with the Food Commodity Intake Database (DEEM-FCIDTM, 

version 7.87) from Exponent. All consumption data for these assessments was taken 

from the USDA’s Continuing Survey of Food Intake by individuals (CSFII) with the 

1994-96 consumption database and the Supplemental CSFII children’s survey 

(1998) consumption database. The acute exposure assessment was based on all 

established and proposed tolerances for S-metolachlor and the percent of crop 

treated was assumed to be 100% for all commodities. Proposed S-metolachlor 

tolerances include carrot, cucumber, okra, sesame seed, sweet sorghum, leafy 

brassica greens subgroup 5B, melon crop subgroup 9A, caneberry crop subgroup 

13A, bushberry crop subgroup 13B, and Onion bulb subgroup 3-07A and 3-07B. 

The chronic exposure assessment was based on field trial residues, UDSA-PDP 
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residues and Syngenta’s 1999-2000 Market Basket Survey (SMBS) residues. For 

the chronic assessment, field trial residues were averaged and entered into the 

DEEM-FCIDTM software with an adjustment for percent of crop treated if such 

information was available. The percent of crop treated was assumed to be 100% for 

the market basket data and for all commodities for which no percent of crop treated 

information was available.

i. Food. Acute Risk. The acute dietary risk assessment was performed for all 

population subgroups with an acute reference dose of 3.0 mg/kg-bw/day based on an 

acute no observable adverse effect level (NOAEL) of 300 mg/kg/day prenatal 

developmental toxicity study in rats and an uncertainly factor of 100X. The 100X 

safety factor includes intra- and interspecies variations. No additional FQPA safety 

factor was applied. The acute assessment was run using DEEM-FCIDTM software 

using established and proposed tolerances for S-metolachlor and 100% crop treated 

value. For the purpose of the aggregate risk assessment, the exposure value was 

expressed in terms of margin of exposure (MOE), which was calculated by dividing 

the NOAEL by the exposure for each population subgroup. In addition, exposure 

was expressed as a percent of the acute reference dose (%aRfD). Acute food (alone) 

exposure to the U.S. population resulted in a MOE of 71,317 (0.14 % of the acute 

RfD of 3.0 mg/kg-bw/day). Acute food (alone) exposure to the most sensitive 

subpopulation (children 1 to 2 years old) resulted in a MOE of 35,110 (0.28% of the 

acute RfD of 3.0 mg/kg-bw/day). Since the benchmark MOE for this assessment 

was 100 and since the EPA generally has no concern for exposures below 100% of 

the RfD, Syngenta believes that there is a reasonable certainty that no harm will 

result from acute dietary (food) exposure to residues arising from the current and 

proposed uses for S-metolachlor.

Chronic Risk. The chronic assessment was run using DEEM-FCIDTM software 

using average field trial residue values, USDA-PDP residues and SMBS data for all 

current and proposed crop registrations. The chronic dietary risk assessment was 

performed for all population subgroups with a chronic reference dose of 0.1 mg/kgbw/day based on a one-year feeding study in dogs with a NOAEL of 9.7 mg/kg/day 

and an uncertainly factor of 100X. The 100-fold safety factor includes intra- and 

interspecies variations. No additional FQPA safety factor was applied. For the 

purpose of the aggregate risk assessment, the exposure values were expressed in 

terms of margin of exposure (MOE), which was calculated by dividing the NOAEL 

by the exposure for each population subgroup. In addition, exposure was expressed 

as a percent of the reference dose (%RfD). Chronic food (alone) exposure to the 

U.S. population resulted in a MOE of 34,761 (0.3% of the chronic RfD of 0.1 mg/kgbw/day). Chronic food (alone) exposure to the most exposed sub-population 

(children, 1-2 years old) resulted in a MOE of 14,616 (0.7% of the chronic RfD of 0.1 

mg/kg-bw/day). Since the benchmark MOE for this assessment was 100 and since 

EPA generally has no concern for exposures below 100% of the RfD, Syngenta 

believes that there is a reasonable certainty that no harm will result from chronic 

dietary (food) exposure to residues arising from the current and proposed uses for 

S-metolachlor.
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Cancer. S-metolachlor has been classified as a Group C, possible human carcinogen 

based on the occurrence of liver tumors in rats. The NOAEL that was established 

based on tumors in rats (15 mg/kg/day) is comparable to the NOAEL of 9.7 

mg/kg/day selected for the chronic reference dose. Therefore the chronic dietary 

end point is protective for cancer dietary (food and water) exposure.

ii. Drinking water. [The estimated drinking water concentrations (EDWCs) 

for surface water and groundwater were taken from monitoring data from two 

National Water Quality Assessment (NAWQA) programs. The maximum 

concentration of parent metolachlor / S-metolachlor detected in a nationwide 

NAWQA surface water monitoring program (that did not analyze for the 

degradates) was used as the peak surface water EDWC for the acute assessment; the 

maximum time-weighted mean from the same database was used as the chronic 

surface water EDWC. For the metolachlor ethanesulfonic acid (ESA) and 

metolachlor oxanilic acid (OA) metabolites, maximum surface water concentrations 

from a NAWQA monitoring program (that collected both surface and groundwater 

data on parent metolachlor / S-metolachlor and the ESA and OA degradates) in the 

midwest cornbelt states of Iowa and Illinois were used as peak surface water 

EDWCs for the acute assessment; maximum time weighted means were used as the 

chronic surface water EDWCs. All groundwater EDWCs were taken from the 

NAWQA Iowa / Illinois monitoring program. Maximum (upper bound) detections 

of parent metolachlor / S-metolachlor and the ESA and OA metabolites from the 

groundwater monitoring were used for both acute and chronic groundwater 

EDWCs since weighted means were not available.

For surface water, the EDWCs of parent metolachlor / S-metolachlor and its 

degradates for acute exposures were estimated to be 96.75 ppb for surface water 

(parent: 77.6 ppb, ESA: 12.4 ppb, and OA: 6.75 ppb) and 109.9 ppb for ground 

water (parent: 32.8 ppb, ESA: 63.7 ppb, and OA: 13.4 ppb). The EDWCs for 

chronic exposures were estimated to be 13.87 ppb for surface water (parent: 4.3 

ppb, ESA: 7.3 ppb, and OA: 2.27 ppb) and 109.9 ppb for ground water (parent: 32.8

ppb, ESA: 63.7 ppb, and OA: 13.4 ppb). 

Acute Exposure from Drinking Water. The acute EDWC of 109.9 ppb for ground

water was used directly in the DEEM-FCIDTM software as “water, direct and 

indirect, all sources” to model the acute drinking water exposures. The acute 

drinking water exposure contributions at the 95%-ile of exposures were determined 

by taking the difference between the aggregate (food + drinking water) exposures 

and the food (alone) exposures for each population subgroups. Acute drinking 

water exposure to the U.S. population resulted in a MOE of 63,884 (0.16% of the 

acute RfD of 3.0 mg/kg-bw/day). Acute drinking water exposure to the most 

exposed sub-population (infants, <1 year old) resulted in a MOE of 17,133 (0.58% of 

the acute RfD of 3.0 mg/kg-bw/day). Since the benchmark MOE for this assessment 

was 100 and since EPA generally has no concern for exposures below 100% of the 
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acute RfD, Syngenta believes that there is a reasonable certainty that no harm will 

result from acute drinking water exposure to residues arising from the current and 

proposed uses for S-metolachlor.

Chronic Exposure from Drinking Water. The predicted chronic ground water 

value of 109.9 ppb was input directly into the DEEM-FCIDTM software as water, 

direct and indirect, all sources to model the chronic drinking water exposure. 

Chronic drinking water exposure to the U.S. population resulted in a MOE of 4,187

(2.30% of the chronic RfD of 0.1 mg/kg-bw/day). Chronic drinking water exposure 

to the most exposed sub-population (infants, <1 year old) resulted in a MOE of 1,277 

(7.6% of the chronic RfD of 0.1 mg/kg-bw/day). Since the benchmark MOE for this 

assessment was 100 and since EPA generally has no concern for exposures below 

100% of the chronic RfD, Syngenta believes that there is a reasonable certainty that 

no harm will result from chronic drinking water exposure to residues arising from 

the current and proposed uses for S-metolachlor.

2. Non-dietary exposure. There is a potential for post-application exposure to 

adults and children resulting from the use of S-metolachlor on residential lawns. 

Post-application exposure is considered to be short-term based on label directions 

limiting application to one time per season. Since toxicity was not observed in a 

dermal toxicity study, up to a dose level of 1,000 mg/kg/day, the only parameter of 

short-term residential risk that needs to be addressed is the possible oral exposure 

of toddlers and children from treated turf or soil. For aggregate risk assessments, 

the EPA recommended using the three scenarios (hand-to-mouth, object-to-mouth, 

soil ingestion) combined. Using these exposure assumptions for short-term 

exposures, the EPA has concluded that aggregated food and residential exposures 

from metolachlor/S-metolachlor result in an aggregate MOE of 991 for children, 1-6

years. Note that there are no non-dietary contributions to the aggregate MOE for 

adults or infants (<1 year) from turf uses since none of the oral exposure scenarios 

(hand-to-mouth, object-to-mouth, soil ingestion) would be applicable to these 

population subgroups.

D. Cumulative Effects

Cumulative Exposure to Substances With a Common Mechanism of 

Toxicity. Section 408(b)(2)(D)(v) 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 has 

examined the common mechanism potential for S-metolachlor and has concluded 

that S-metolachlor should not be included with the chloroacetanilide pesticides 

designated as a “Common Mechanism Group.” The Agency’s position is that only 

some chloroacetanilides, namely acetochlor, alachlor and butachlor should be 

considered as a “Common Mechanism Group” due to their ability to cause nasal 

turbinate tumors.
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E. Safety Determination

1. U.S. population. Using the conservative assumptions described above, and 

based on the completeness and reliability of the toxicity data, the acute aggregate 

exposure calculation for current and proposed uses of S-metolachlor provided a

MOE of 33,698 (0.3% of the acute RfD of 3.0 mg/kg-bw/day) for the U.S. 

population. The chronic aggregate exposure calculation for current and proposed 

uses of S-metolachlor provided a MOE of 3,738 (2.6% of the chronic RfD of 0.1 

mg/kg-bw/day) for the U.S. population. Since the aggregate MOEs exceed the 

benchmark MOE of 100, Syngenta believes that there is a reasonable certainty that 

no harm will occur to the U.S. Population from acute or chronic aggregate 

exposures arising from the current and proposed uses for S-metolachlor.

2. Infants and children. Using the conservative assumptions described in the 

exposure section above, and based on the completeness and reliability of the toxicity 

data, the acute aggregate exposure calculation for current and proposed uses of Smetolachlor provided a MOE of 12,065 (0.83% of the acute RfD of 3.0 mg/kgbw/day) for the infants < 1 year old (the most sensitive population subgroup for the 

acute assessment). The chronic aggregate exposure calculation for current and

proposed uses of S-metolachlor provided a MOE of 1,215 (8.0% of the chronic RfD 

of 0.1 mg/kg-bw/day) for the infants < 1 year old (the most sensitive population 

subgroup for the chronic assessment). Since the aggregate MOEs exceed the 

benchmark MOE of 100, Syngenta believes that there is a reasonable certainty that 

no harm will occur to infants and children from acute or chronic aggregate 

exposures arising from the current and proposed uses for S-metolachlor.

F. International Tolerances

There are currently no Maximum Residue Limits (MRLs) set for Smetolachlor for crops by the Codex Alimentarius Commission. International MRLs 

for the herbicide S-metolachlor have been established for various agricultural 

commodities in a number of countries including Argentina, Australia, Austria, 

Belarus, Belgium, Brazil, Canada, Czech Republic, France, Georgia, Germany, 

Greece, Hungary, India, Italy, Japan, Korea (South), Luxembourg, Malaysia, 

Moldova, Morocco, Netherlands, New Zealand, Russia, Serbia and Montenegro, 

Slovak Republic, Slovenia, Spain, Switzerland, Taiwan, and Ukraine.