1 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

Date: December 3, 2014

PC Codes: 108800, 108801

DP Barcode: 420467

MEMORANDUM 

SUBJECT: Registration Review Problem Formulation for Metolachlor and S-Metolachlor 

FROM: Robin Sternberg, Ph.D., Wildlife Biologist 

 Christopher M. Koper, M.S., Chemist 

 Environmental Risk Branch 1 

Environmental Fate and Effects Division (7507P) 

THROUGH: Sujatha Sankula, Ph.D., Branch Chief 

 Meghan Radtke, Ph.D., Acting RAPL 

Environmental Risk Branch 1 

 Environmental Fate and Effects Division (7507P) 

 

TO: Steven Snyderman, Risk Review Manager 

 Avivah Jakob, Team Leader 

 Patricia Parrott, Branch Chief 

Risk Management and Implementation Branch 3 

Pesticide Re-Evaluation Division (7508P) 

Attached is the Registration Review Problem Formulation for the herbicides metolachlor (PC 

code 108801) and S-metolachlor (PC code 108800). 

 
2 

REGISTRATION REVIEW 

PROBLEM FORMULATION ______________________________________________________________________________ 

 Metolachlor and S-Metolachlor 

CAS Numbers: 51218-45-2 (metolachlor) and 87392-12-9 (S-metolachlor) 

US EPA PC Codes: 108801 (metolachlor) and 108800 (S-metolachlor) 

Prepared by: 

Robin Sternberg, Ph.D., Wildlife Biologist 

Christopher M. Koper, M.S., Chemist 

Environmental Risk Branch 1 

Reviewed by: 

Edward Odenkirchen, Ph.D., Senior Advisor 

Stephen Wente, Ph.D., Biologist 

Environmental Risk Branch 1 

U.S. Environmental Protection Agency 

Office of Pesticide Programs 

Environmental Fate and Effects Division 

Environmental Risk Branch I 

1200 Pennsylvania Ave., NW 

Mail Code 7507P 

Washington, DC 20460 
3 

1 Executive Summary 

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

formulation (attached) for the ecological risk, environmental fate, endangered species, and 

drinking water assessments to be conducted as part of the Registration Review of metolachlor 

and S-metolachlor. For simplicity, metolachlor is used to represent the 1:1 mixture of (R)- and 

(S)-enantiomers of metolachlor in the document and S-metolachlor represents the more Senantiomer enriched registration. The problem formulation describes the methods planned to be 

used during the completion of drinking water and ecological risk assessments in support of 

Registration Review and provides an overview of the environmental fate, ecological effects, and 

potential risks associated with the use of metolachlor/S-metolachlor as well as uncertainties 

unique to risk assessment of metolachlor/S-metolachlor. This document also identifies 

additional studies that would be beneficial for conducting an ecological risk assessment. Major 

findings include the following data needs: 

 OCSPP 835.4100: Aerobic Soil Metabolism: 2 additional soils 

(metolachlor or S-metolachlor, TGAI) 

 OCSPP 835.4200: Anaerobic Soil Metabolism: 3 additional soils 

(metolachlor or S-metolachlor, TGAI) 

 OCSPP 835.4300: Aerobic Aquatic Metabolism: 1 additional sediment system 

(metolachlor or S-metolachlor, TGAI) 

 OCSPP 835.4400: Anaerobic Aquatic Metabolism: 1 additional sediment system 

(metolachlor or S-metolachlor, TGAI) 

 OCSPP 850.7100: ECM/ILV: method and independent validation in soil and independent 

validation in water. (metolachlor or S-metolachlor, TGAI) 

 OCSPP 850.2100: Avian acute oral toxicity test, passerine species (metolachlor or Smetolachlor, TGAI) 

 OCSPP 850.4100: Seedling emergence and seedling growth 

– S-metolachlor (TEP): four species of dicots, one of which is soybean 

– Degradate Metolachlor-ESA (TGAI): ryegrass, tomato, and carrot 

– Degradate Metolachlor-OA (TGAI): onion 

 OCSPP 850.4150: Vegetative vigor 

– S-metolachlor (TEP): four species of dicots, one of which is soybean 

 Non-guideline study: Chronic oral toxicity to adult honey bees (metolachlor or Smetolachlor, TGAI) 

 Non-guideline study: Chronic oral toxicity to larval honey bees extended to include an 

acute endpoint (metolachlor or S-metolachlor, TGAI) 

 Non-guideline study: Pollen and nectar residue studies (metolachlor or S-metolachlor, 

TGAI) – The need for these studies is contingent upon the results of lower tier bee studies 

 OCSPP 850.3040: Semi-field and field testing for pollinators (metolachlor or Smetolachlor, TGAI) – The need for field testing is contingent upon the results of lower 

tier bee studies 

 Non-Guideline: Whole sediment: chronic invertebrates, freshwater and marine 

(metolachlor or S-metolachlor, TGAI) 
4 

 Label clarifications: specifically including an annual maximum application rate, the 

maximum number of applications allowed per year (and crop cycle, if applicable), 

minimum application interval, and a lb a.i./A application rate for the ornamental band 

treatment use. 

As previously stated in a 2002 EFED memo (USEPA, 2002), the ecological effects data are 

supportive of bridging toxicity profiles of metolachlor and S-metolachlor. Therefore, similar to 

assessments in the past, the most sensitive endpoints from registrant-submitted guideline studies 

or open literature studies will be used for the Registration Review ecological risk assessment 

regardless of whether the endpoint is derived from a study conducted with metolachlor or Smetolachlor. 

2 Introduction 

Metolachlor and S-metolachlor have separate registrations. Metolachlor (PC 108801), also 

known as racemic metolachlor, was first registered in 1976 and is a 1:1 mixture of (R)- and (S)-

enantiomers of metolachlor. S-metolachlor (PC 108800), conditionally registered in 1997, is 

enantomerically enriched with the more active (S)-enantiomer (i.e., 12% (R): 88% (S)). 

Metolachlor and S-metolachlor are pre-plant incorporated/pre-emergence/early post-plant broadspectrum herbicides in the chloroacetamide chemical family used to control grasses and 

broadleaf weeds in non-agricultural (S-metolachlor only) and/or agricultural (both) settings. 

Metolachlor and S-metolachlor act via inhibiting seedling shoot and meristematic growth. 

EFED evaluated the most recent ecological risk assessments for metolachlor in association with 

updated toxicity, exposure, and usage information to determine if sufficient data are available 

and if further updates are needed to support Registration Review. In addition, EFED considered 

the latest Agency science policies and risk assessment methodologies. 

3 Use Characterization 

Metolachlor and S-metolachlor are pre-plant incorporated/pre-emergence/early post-plant broad 

spectrum herbicides in the chloroacetamide chemical family used to control seedling grasses, 

nutsedges, and certain annual broadleaf weeds such as nightshades, lambs quarter, and pigweeds 

in both agricultural and non-agricultural settings. It is registered for several major and minor 

food uses. Products containing metolachlor or s-metolachlor are applied using aerial and ground 

equipment. The chemical profile produced by BEAD, compiled into Appendix A and Appendix 

B, lists the use patterns of maximum exposures (based on pounds of active ingredient applied) 

for the current uses of metolachlor and S-metolachlor. EFED will use application scenarios that 

result in maximum exposure scenarios for a given use for the risk assessment. There is some 

missing label information in some of the labels. Specifically, many of the national and special 

local needs uses for metolachlor and s-metolachlor are missing maximum yearly application 

rates. Many of these labels only report a seasonal maximum application; however, some of the 

crops may be grown multiple times per year. Consequently, the label should be clarified to 

indicate a maximum yearly application rate and/or the maximum number of seasons (crop 

cycles) in one year for that crop. Many labels did not specify the number of applications that 

could be made. In some instances, the number of applications could be estimated based on the 
5 

yearly or seasonal maximum application rate. Exceptions to this were: metolachlor – corn, 

peanuts, safflower and soybean; s-metolachlor – alfalfa, broccoli, corn, peanuts, pepper (special 

local needs only), pumpkin, safflower, sorghum and sunflower. In these instances, there was not 

enough information on the label to estimate the number of applications that could be made. The 

minimum application interval was also missing for most uses. Finally, the ornamental band 

treatment application rate could not be converted into lb a.i./A, as needed for environmental 

modeling. See Appendices A and B for detailed information about application rates and where 

assumptions can be made. The absence of a maximum single application rate, an application 

interval or number, a maximum annual application rate (lbs a.i./year), and/or application method 

on labels may result in conservative assumptions. 

4 Conclusions from Previous Risk Assessments 

4.1 Ecological Risk Assessments 

EFED has conducted numerous ecological risk assessments on metolachlor and S-metolachlor 

that serve as a basis for this problem formulation. A table summarizing previous assessments for 

metolachlor/S-metolachlor can be found in Appendix C. Recent ecological risk assessments for 

metolachlor include a 1994 assessment supporting the Agency’s 1995 Re-registration Eligibility 

Decision (RED) (USEPA, D185152 and D172022)1

, a 2006 litigation assessment for 26 

evolutionarily significant units (ESUs) of listed salmonids in the Pacific Northwest, 2007 

litigation assessments for the Barton Springs salamander and California red legged frog (CRLF), 

and a 2010 litigation assessment for the San Francisco Bay (SFB) area species, delta smelt and 

California tiger salamander. Recent ecological risk assessments for S-metolachlor include a 

2010 litigation assessment for the SFB area species, delta smelt and California tiger salamander, 

a 2010 assessment associated with the IR-4 proposed new use on sesame, melon, bushberry, 

caneberry, sorghum, leafy Brassica, turnip greens, carrot, cucumber, okra, dry bulb onions, and 

green onions (DP 370759), a 2011 assessment associated with an emergency exemption for use 

on lettuce in Michigan (DP 390436), and a 2012 assessment associated with the IR-4 proposed 

new use on cilantro and garden beet leaves (DP 392602). The litigation assessments can be 

accessed at: http://epa.gov/espp/litstatus/effects/ (salmonids, Barton Springs salamander) or 

http://epa.gov/espp/litstatus/effects/redleg-frog/index.html (CRLF, SFB area species). 

The most recent, comprehensive assessment conducted for metolachlor and S-metolachlor is a 

section 3 action for the use of S-metolachlor on cilantro and garden beet leaves (USEPA 2012, 

D392602), which was issued in 2012. The major ecological conclusions presented in the section 

3 ecological risk assessment were as follows: 

Table 1. Summary of Risk Concerns Identified for S-Metolachlor1

 in Most Recent Section 3 

Ecological Risk Assessment for Use on Cilantro and Garden Beet Leaves 

Birds Mammals Terr. 

Plants 

Terr. 

Inverts 

Fish Bioaccumulation 

Factor 

Aquatic 

Inverts 

Aquatic 

Plants 

Groundwater 

Contamination 

Persistence Degradates

of Concern

Yesa Yesa Yes No No No Yesa Yes Yes Yesb Yes 1

The assessment was conducted on S-metolachlor, but the conclusions would be similar for metolachlor. 

 

1 http://www.epa.gov/oppsrrd1/REDs/0001.pdf
6 

Yes =at least one LOC has been exceeded in previous assessments; "No" = LOCs have not been exceeded in 

previous assessments; NA = RQs have not been calculated previously. a

 Levels of Concern exceeded from chronic exposure. Risk to birds (surrogate for terrestrial-phase amphibians and 

reptiles) consuming short grass exclusively from use on garden beet leaves. 

b

 Persistence is a function of environmental conditions as degradation is dependent on microbially-mediated and 

abiotic processes. 

Collectively, the historical assessments of metolachlor/S-metolachlor have identified the 

potential for risk to: 

 mammals (listed and non-listed, chronic exposure), 

 birds (listed and non-listed, chronic exposure), 

 terrestrial plants, 

 freshwater fish (listed, acute exposure; listed and non-listed, chronic exposure), 

 freshwater invertebrates (listed and non-listed, chronic exposure), and 

 aquatic vascular and non-vascular plants. 

4.2 Drinking Water Exposure Assessments 

A drinking water exposure assessment was conducted in 2010 for S-metolachlor and its 

degradates ethanesulfonic acid (ESA) and oxanilic acid (OA) in association with the IR-4 

proposed new use on sesame, melon, bushberry, caneberry, sorghum, leafy Brassica, turnip 

greens, carrot, cucumber, okra, dry bulb onions, and green onions. Due to the extensive water 

monitoring data available for metolachlor/S-metolachlor, estimated drinking water 

concentrations (EDWCs) were a combination of modelling and monitoring data (USEPA. 2010. 

D368735). 

4.3 Clean Water Act Programs 

Metolachlor and S-metolachlor are not identified as a cause of impairment for any water bodies 

listed as impaired under section 303(d) of the Clean Water Act. No Total Maximum Daily Load 

(TMDL) criteria have been developed for metolachlor or S-metolachlor. Aquatic benchmarks 

have been established for metolachlor and S-metolachlor and are available at 

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

otherwise located as part of the Registration Review process may be used to update aquatic life 

benchmarks, if applicable. 

5 Environmental Fate and Transport 

Metolachlor is a racemic mixture of R- and S-enantiomers (stereo isomers that are mirror 

images). Metolachlor is composed of approximately equal proportions of the R and S

enantiomers, whereas S-metolachlor is an enrichment comprised almost solely of the S

enantiomer (88% S-isomer). Enantiomers have the same chemical and physical properties except 

for the direction they rotate plane polarized light. The Agency has concluded that environmental 

behavior of metolachlor and S-metolachlor is expected to be similar. Therefore, the 

environmental fate data were bridged from metolachlor to S-metolachlor (USEPA, 2002). 
7 

Environmental fate data indicate that parent metolachlor/S-metolachlor appear to be moderately 

persistent to persistent. Metolachlor/S-metolachlor degradation appears to be dependent of 

microbially-mediated (aerobic soil metabolism t1/2 = 13.9 to 67 days; anaerobic soil metabolism 

t1/2 =81 days) and abiotic processes (photodegradation in water t1/2 = 70 days under natural 

sunlight and photodegradation on soil t1/2 = 8 days under natural sunlight). 

Depending on the soil (i.e. organic matter content), metolachlor/S-metolachlor has the potential 

to be mobile to moderately mobile with Koc values ranging from 21.6 to 369 mL/g oc and have 

been detected extensively in surface water and groundwater. The Agency concluded that there is 

no difference in soil sorption affinity between metolachlor and S-metolachlor as there were 

similar Koc coefficients in the batch equilibrium studies conducted on both active ingredients 

independently [mean Koc=135 (racemic) and 219 (S-enriched)] (USEPA 2002). 

Field dissipation studies indicate that metolachlor/S-metolachlor is persistent in surface soil with 

half-lives ranging from 3 to 292 days in the upper six inch soil layer depending on geographic 

location. Metolachlor/S-metolachlor was reportedly detected as deep as 36 to 48 inches in some 

of the studies. 

The Metolachlor Task Force (MTF) has conducted a small scale prospective groundwater study 

(MRIDs 47017401-04) for metolachlor in order to comply with the request of groundwater data 

for conditional registration of the technical metolachlor. The residue sample collection was 

initiated in June 2003 continuing through 939 days after application. The objective was to 

determine the potential for the active ingredient metolachlor and its degradates (CGA-37735, 

CGA-51202, CGA-67125, CGA-41638, and CGA-354743) to reach groundwater when used in a 

vulnerable hydrogeologic setting. The study results show that metolachlor and two of its 

degradation products CGA-51202 and CGA-354743 can leach through the vadose zone into 

groundwater when applied in a vulnerable hydrogeologic setting. The detected peak concentrations 

of the degradation products CGA-51202 and CGA-354743 are higher than the detected peak 

metalochlor concentrations. 

Metolachlor appears to have a low potential to bioaccumulate in fish with a reported whole body 

bioconcentration factor of 69X and a whole body elimination of 93% after 14 days depuration. 

The major organic degradates CGA-354743 (metolachlor-ESA; 12.4% formation; MRID 

43928936) and CGA-51202 (metolachlor-OA; 28.1% formation; MRID 31309801A-B) are more 

persistent and mobile than their parent(s) and have been identified in both ground water and 

surface water. Two additional major degradates were identified in aerobic soil metabolism 

studies using Metolachlor and S-metolachlor, CGA-40172 (11.6% formation; MRID 45499606) 

and CGA-50720 (Formation 14.85%; MRID 31309801A-B). The most recent physical, 

chemical, environmental fate and transport properties of metolachlor and S-metolachlor are listed 

in Table 5-1.

Table 5-1. Chemical Properties and Environmental Fate Parameters of Metolachlor and SMetolachlor 

Parameter Value Source/MRID # 

Common Name Metolachlor 

S-Metolachlor 

Product 

Chemistry 
8 

Parameter Value Source/MRID # 

CAS Number 51218-45-2 (Metolachlor) 

87392-12-9 (S-Metolachlor) 

Chemical Name 2-Chloro-N-(2-ethyl-6-methylphenyl)-N-(1-methoxy-2-

propanyl)acetamide (Metolachlor) 

2-Chloro-N-(2-ethyl-6-methylphenyl)-N-[(2S)-1-methoxy2-propanyl]acetamide (S-Metolachlor) 

Chemical Class/Category Chloroacetanilide Herbicide 

Empirical formula C15H22ClNO2

Structure 

Molecular Mass 283.79 g/mole 

Water Solubility 530 mg/L at 20C 

Vapor pressure (25C) 2.78 x 10-5 mm Hg 

Henry’s Law Constant 2.16 x 10-8 atm m3/mol Calculated1

Octanol/water partition 

coefficient (Kow) 1122 (log Kow = 3.05) Product 

Chemistry 

Dissociation Constant (pKa) No dissociation within pH 2-12 Product 

Chemistry 

Hydrolysis at 25C (t1/2) 

pH 5 = stable

pH 7 = stable 

pH 9 = stable 

40430201 

Aqueous Photolysis (t1/2) 

(pH 7) 70 days 40430202 

Soil Photolysis (t1/2) 8 days (natural light) 

37 days (artificial light) 

40430203 

43928935 

Aerobic Soil Metabolism 

25C (t1/2) 

 

67 days (sandy loam) 

50.3 days (sandy clay loam)S

14.9 days (sandy clay loam) S

13.9 days (sandy clay loam) S

41309801 

45499606S 

45499606S 

45499606S

Anaerobic Soil Metabolism 

25C (t1/2) 81 days (sandy loam) 41309801 

Aerobic Aquatic Metabolism 

25C (t1/2) 47 days (sandy loam sediment) 41185701 

Anaerobic Aquatic Metabolism 78 days (sandy loam sediment) 
9 

Parameter Value Source/MRID # 

25C (t1/2) 41185701 

Soil Partition Coefficient (Koc) 

(mL/g) 

369 (clay) 

188 (sand) 

119 (sandy loam) 

110 (silt loam) 

66.7 (clay) 

21.6 (sand) 

110.4 (loam) 

74.4 (sandy loam) 

43928937S

40494604 

Terrestrial Field Dissipation 

(t1/2)

 

112.3 days (GA Bare Soil ) 

3.0 days (GA Grass ) 

20.8 days (GA Thatch ) 

128.1 days (IA Cropped Soil) 

123.8 days (IA Bare Soil) 

144.3 days (IA Cropped Soil) 

117.1 days (IA Bare Soil) 

120.0 days (IA Cropped Soil) 

115 days (IA Bare Soil) 

135 days (IA Cropped Soil) 

152 days (IA Bare Soil) 

132 days (CA Cropped Soil) 

97 days (CA Bare Soil) 

193 days (CA Cropped Soil) 

292 days (CA Bare Soil) 

45848001 

41335701 

41484203 

41335702 

41484204 

41309802 

41484201 

41309803 

41484202 

41309804 

41484205 

41309805 

41484206 

Laboratory Volatility 0.05% volatilized/day (100% humidity) 40494606 

Bioaccumulation in Fish 

(BCF) 

15X edible tissues; 70% depuration phase (14 days) 

159X non-edible tissues; 96% depuration phase (14 days) 

69X whole fish; 93% depuration phase (14 days) 

41154201 

Groundwater Monitoring 

Degradates CGA-51202 and CGA-354743 can leach 

through the vadose zone into groundwater and their 

detected peak concentrations are higher than parent 

metolachlor concentrations when applied in a vulnerable 

hydrogeologic setting. 

47017401 

47017402 

47017403 

47017404 
10 

Parameter Value Source/MRID # 

1

 = Henry’s Law (atm-m3/mole) = (VAPR/760)/(SOL/MWT), where VAPR is vapor pressure in torr, MWT is 

molecular weight in g/mol, and SOL is the solubility in water in mg/L. S = denotes study using S-metolachlor.

5.1 Transformation Products 

The major organic degradates of metolachlor/S-metolachlor in submitted environmental fate 

studies were identified as CGA-354743 (metolachlor ethane sulfonic acid or metolachlor-ESA), 

CGA-51202 (metolachlor oxanilic acid or metolachlor-OA), CGA-40172 and CGA-50720. 

Among these, metolachlor ESA and metolachlor OA are more persistent than their parents and 

have been identified in both ground water and surface water. In addition, a variety of minor 

degradates were observed in a variety of studies. Table 5-2 summarizes the transformation 

products of metolachlor/S-metolachlor and their maximum amounts formed. 
11 

Table 5-2. Metolachlor/S-Metolachlor and Its Environmental Degradates 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRI

Parent 

Metolachlor (CGA-24705) 

CAS Name: (R)2-Chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide CAS Number: 051218-45-2Molecular Weight: 283.80 

g/mol Chemical Formula:

C15H22NO2Cl 

SMILES: CCc1cccc(C)c1N(C(C)COC)C(=O)CCl 

Parent structure shown 

S-Metolachlor (CGA-77102) 

CAS Name: (S)-2-Chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide CAS Number: 087392-12-9 Molecular Weight: 283.80 

g/mol Chemical Formula:

C15H22NO2Cl 

SMILES: Cc1cccc(CC)c1N(C(=O)CCl)C(C)COC

Parent structure shown 

Transformation Products 
12 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRIMetolachlor Oxanilic Acid/ Metolachlor-OA (CGA-51202)

CAS Name: [(2-ethyl-6-methylphenyl) (2-methoxy-1-methylethyl) amino] oxo-acetic acid Molecular Weight: 389.06 g/mol Chemical Formula: C15H21NO4 

SMILES: COCC(N(c1c(C)cccc1CC)C(=O)C(=O)O)C

Aqueous Photolysis 404302Aerobic Soil Metabolism 454996Aerobic Soil Metabolism 439289Aerobic Soil Metabolism 313098

A-B 

Anaerobic Soil Metabolism 313098

A-B 

Terrestrial Field Dissipation 458480

Metolachlor ethane sulfonic acid/ MetolachlorESA (CGA-354743) 

CAS Name: 2-((2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino)-2-oxoethanesulfonic acid Molecular Weight: 329 g/mol Chemical Formula:

C15H23NO5S 

SMILES: O=S(=O)(O)CC(=O)N(c1c(cccc1CC)C)C(COC)C (chem spider) 

Aerobic Soil Metabolism 454996

Aerobic Soil Metabolism 439289Terrestrial Field Dissipation 458480
13 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRICGA-41507 CAS Name: 

N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl) acetamide Molecular Weight: 249.36 g/mol Chemical Formula:C15H23NO2

Aerobic Aquatic Metabolism 411857

Anaerobic Aquatic Metabolism 411857

CGA-40172 CAS Name: 

Not reported Molecular Weight: 346.03 g/mol Chemical Formula:

C15H23NO3SMILES: c1c(c(c(cc1)C)N(C(=O)(CO))C(COC)C)CC 

Aerobic Aquatic Metabolism 411857Anaerobic Aquatic Metabolism 411857Aerobic Soil MetabolismS 454996

CGA-41638 CAS Number: 65513-61-3

Molecular Weight: 346.03 g/mol 

Aqueous Photolysis 404302

Aerobic Soil Metabolism 313098

A-B 
14 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRI

Chemical Formula:C14H26ClNO2SMILES: 

Anaerobic Soil Metabolism 313098

A-B 

CGA-50720 CAS Name: Not assigned

Molecular Weight: 346.03 

g/mol 207.23 (Pubchem) Chemical Formula:C11H13NO3

SMILES: CCc1cccc(c1NC(=O)C(=O)O)C 

Aerobic Aquatic Metabolism 411857Aqueous Photolysis 404302Aerobic Soil Metabolism 413098

A-B 

Anaerobic Soil Metabolism 413098

A-B 

CGA-37913 CAS Name: not reported 

Molecular Weight: not reported g/mol Chemical Formula: not reported SMILES: not reported 

Anaerobic Aquatic Metabolism 411857

CGA-37735 CAS Name: not reported 

Molecular Weight: not reported g/mol Chemical Formula: not reported 

Aerobic Soil Metabolism 313098

A-B 
15 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRI

SMILES: not reported 

Anaerobic Soil Metabolism 313098

A-B 

CGA-13656 CAS Name: not reported 

Molecular Weight: not reported g/mol Chemical Formula: not reported SMILES: not reported 

Aerobic Soil Metabolism 313098

A-B 

Anaerobic Soil Metabolism 313098

A-B 

CGA-46129 CAS Name: not reported 

Molecular Weight: not reported g/mol Chemical Formula: not reported SMILES: not reported 

Aqueous Photolysis 404302

CGA-46127 CAS Name: 

Aerobic Aquatic Metabolism 411857
16 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRI

N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-2-(methylthio)acetamide Molecular Weight: 295.44 g/mol Chemical Formula:C16H25NO2S 

Anaerobic Aquatic Metabolism 411857

NOA-436611 (STGA) 

sulfoxide of thioglycolic acid 

Aerobic Soil Metabolism 454996

CGA-46576 

Aerobic Soil Metabolism 454996

CO2 Carbon Dioxide O=C=O Aerobic Soil Metabolism 454996

Aerobic Soil Metabolism 439289

Organic Volatiles 

Aerobic Soil Metabolism 454996

Aerobic Soil Metabolism 413098

A-B 
17 

Code Name/ Synonym Chemical Name Chemical Structure Study Type MRIUnextractable Residues Aerobic Soil Metabolism 413098

A-B 

Anaerobic Soil Metabolism 413098

A-B 

Note: Bold values denote major (> 10%) degradates. 
18 

6 Receptors 

6.1 Metolachlor and S-Metolachlor 

As previously stated in a 2002 EFED memo (USEPA, 2002), the ecological effects data are 

supportive of bridging toxicity profiles of metolachlor and S-metolachlor. Although the studies 

were not conducted using identical test conditions and procedures, the toxicity of metolachlor 

and S-metolachlor are similar except for the risk to non-target terrestrial plants (Table 6-1). 

Specifically, the only difference in risk is associated with a slightly greater risk of S-metolachlor 

to non-target terrestrial plants. Therefore, similar to assessments in the past, the most sensitive 

endpoints from registrant-submitted guideline studies or open literature studies will be used for 

the Registration Review ecological risk assessment regardless of whether the endpoint is derived 

from a study conducted with metolachlor or S-metolachlor. Summaries of the most sensitive 

endpoints used to characterize the toxicity of metolachlor/S-metolachlor to non-target organisms 

are provided in Table 6-2. Summaries of all submitted metolachlor and S-metolachlor toxicity 

data can be found in Appendix D. 

For metolachlor/S-metolachlor, no data are available for the following: 

 acute oral toxicity to a passerine species; 

 chronic oral toxicity to adult honey bees; 

 acute and chronic oral toxicity to honey bee larvae; and 

 toxicity to benthic invertebrates. 

Metolachlor/S-metolachlor is classified as: up to moderately toxic to fish and aquatic 

invertebrates on an acute basis; practically non-toxic to birds on acute oral and sub-acute dietary 

bases; and practically non-toxic to adult honey bees on acute contact and oral bases. 

6.2 Degradates 

Summaries of the endpoints used to characterize the toxicity of the major degradates of 

metolachlor/S-metolachlor, metalochlor-OA (CGA-51202) and metolachlor-ESA (CGA354743), to non-target organisms are provided in Table 6-3. Toxicity data are available for 

terrestrial plants, freshwater fish (acute), freshwater aquatic invertebrates (acute), aquatic 

vascular plants, and aquatic nonvascular plants. 

In general, the degradates are less toxic to non-target organisms than metolachlor/S-metolachlor. 

Specifically, metolachlor-OA and metolachlor-ESA are one, three, and two orders of magnitude 

less toxic to aquatic animals, aquatic plants, and terrestrial plants, respectively, than 

metolachlor/S-metolachlor.
19 

Table 6-1. Comparison of Toxicity Endpoints for Metolachlor and S-Metolachlor and Degradates MetolacMetolachlor-ESAa

Study type Species Endpoint Metolachlor 

(CGA-77102) 

S-Metolachlor

(CGA-24705) 

Meto

O

(CGA

Avian acute oral Mallard duck LD50 (mg/kg-bw) 4640 >2194 

NOAEL (mg/kg-bw) Not specified 2194 

Bobwhite quail LD50 (mg/kg-bw) >2194 

NOAEL (mg/kg-bw) 874 

Avian sub-acute dietary Mallard duck LC50 (mg/kg-diet) >10,000 >4912 

NOAEC (mg/kg-diet) Not specified 1556 

Bobwhite quail LC50 (mg/kg-diet) >10,000 >4912 

NOAEC (mg/kg-diet) Not specified 2762 

Avian reproduction Mallard duck NOAEC (mg/kg-diet) 800 

Bobwhite quail NOAEC (mg/kg-diet) 403 1000 

Mammalian acute oral Rat LD50 (mg/kg-bw) 2780 3267 Mammalian reproduction Rat NOAEC (mg/kg-diet) 300 Acute oral with adult bees Honey bee LD50 (μg/bee) >110 >200 Acute contact with adult bees Honey bee LD50 (μg/bee) >110 >85 Terrestrial plant seedling emergence Monocot EC25 (lb/A) 0.017 0.0048 >

NOAEC/EC05 (lb/A) 0.0031 0.0010 <

Dicot EC25 (lb/A) 0.09 0.0057 >

NOAEC/EC05 (lb/A) 0.012 0.0003 <

Terrestrial plant vegetative vigor 

Monocot EC25 (lb/A) 0.016 0.021 >

NOAEC/EC05 (lb/A) 0.0031 0.011 

Dicot EC25 (lb/A) 0.030 0.27 >

NOAEC/EC05 (lb/A) 0.025 0.01 

Acute freshwater fish Rainbow trout LC50 (mg/L) 3.80 11.9 >

NOAEC (mg/L) Not specified 2.5 9

Bluegill sunfish LC50 (mg/L) 10.3 3.2 

NOAEC (mg/L) 6.0 1.5 

Chronic freshwater fish Fathead minnow NOAEC (mg/L) 0.030 Acute estuarine/marine fish Sheepshead minnow LC50 (mg/L) 7.9 16.8 

NOAEC (mg/L) 3.6 6.04 

Chronic estuarine/marine fish Sheepshead minnow NOAEC (mg/L) 1.0 Acute freshwater aquatic invertebrate Water flea 

(Ceriodaphnia dubia or Daphnia 

EC50 (mg/L) 25.1 (registrant)

1.1 (ECOTOX)

26 (registrant) 1

NOAEC (mg/L) 5.6 (registrant) 4.8 (registrant) 
20 

Study type Species Endpoint Metolachlor 

(CGA-77102) 

S-Metolachlor

(CGA-24705) 

Meto

O

(CGA

magna)

Chronic freshwater aquatic invertebrate Daphnia magna NOAEC (mg/L) 3.2 (registrant) 

0.001 (ECOTOX)

5.17 (registrant)

0.1 (ECOTOX)

Acute estuarine/marine mollusc Eastern oyster EC50 (mg/L) 1.6 

NOAEC (mg/L) 0.71 

Acute estuarine/marine invertebrate Mysid shrimp LC50 (mg/L) 4.95 

NOAEC (mg/L) 2.3 

Chronic estuarine/marine invertebrate Mysid shrimp NOAEC (mg/L) 0.00013 Aquatic vascular plant Lemna EC50 (mg/L) 0.048 0.021 >

NOAEC (mg/L) 0.0084 0.0076 9

Aquatic nonvascular plant Green alga EC50 (mg/L) 0.010 0.0080 5

NOAEC (mg/L) 0.0007 0.0015 2

Freshwater diatom EC50 (mg/L) 0.38 18 

NOAEC (mg/L) 0.0037 4.08 

Marine diatom EC50 (mg/L) 0.061 0.11 

NOAEC (mg/L) 0.0017 0.021 

Cyanobacterium EC50 (mg/L) 1.2 21 

NOAEC (mg/L) 0.063 9.6 

a shaded, empty cells indicate that there are no data available Table 6-2. Summary of Most Sensitive Endpoints from Toxicity Studies with Metolachlor/S-Metolachlor 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Avian acute oral: single dose, 8-day observation (instead of usual 14-day observation) 

Metolachlor technical (NS) 

Mallard duck (Anas platyrhynchos) 

LD50 (95% C.I.) = 4640 (3000-7200) mg/kg-bw (nom) 

NOAEC : Not specified Practically non-toxic 

Avian acute oral: single dose, 14-day observation 

S-Metolachlor technical (87.4) 

Mallard duck (Anas platyrhynchos) 

LD50 > 2194 mg a.i./kg-bw (m) 

NOAEC = 2194 mg a.i./kg-bw (m) (no sublethal effects or treatment-related mortality) Practically non-toxic 
21 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Avian acute oral: single dose, 14-day observation 

S-Metolachlor technical (87.4) 

Bobwhite quail (Colinus virginianus) 

LD50 > 2194 mg a.i./kg-bw (m) 

NOAEC = 874 mg a.i./kg-bw (m) LOAEC = 1390 mg a.i./kg-bw (m) (no mortality; body weight losses at ≥1390 mg/kg-bw) Practically non-toxic 

Avian acute oral Metolachlor Passerine species No data Avian sub-acute dietary: 5-day exposure; 3-day post-exposure observation 

S-Metolachlor technical (87.4) 

Mallard duck (Anas platyrhynchos)

LC50 > 4912 mg/kg-diet (m) 

NOAEC = 1556 mg a.i./kg-diet (m) LOAEC = 2762 mg a.i./kg-diet (m) (20% [2/10] mortality at 874 mg/kg-diet; NOAEC based on slight reduction in body weight gain at ≥2762 mg/kg-diet du

the first 5 days of the test) Practically non-toxic 

S-Metolachlor technical (87.4) 

Bobwhite quail (Colinus virginianus) 

LC50 > 4912 mg/kg-diet (m) 

NOAEC = 2762 mg a.i./kg-diet (m) LOAEC = 4912 mg a.i./kg-diet (m) (no mortality; NOAEC based on slight reduction in body wegain at 4912 mg/kg-diet during the first 5 days of the test) Practically non-toxic 

Avian reproduction: ~20 weeks (chronic) 

Metolachlor technical (97.2) 

Bobwhite quail (Colinus virginianus) 

NOAEC = 403 mg a.i./kg-diet (mm) LOAEC = 1010 mg a.i./kg-diet (mm) (based on increase in cracked eggs) 

Avian reproduction: 20 weeks (chronic) 

Metolachlor technical (97.3) 

Mallard duck (Anas platyrhynchos) 

NOAEC = 800 mg a.i./kg-diet (nom) LOAEC > 800 mg a.i./kg-diet (nom) (no treatment-related effects) 

Mammalian acute oral, limit: single dose; 7-day observation (instead of usual 14-day observation) 

Metolachlor (NS) 

Rat (Rattus norvegicus) 

LD50 (95% C.I.) = 2780 (2180-3545) mg/kg-bw 

(20,30, 50, and 100% mortality at 1670, 2150, 2780, and 464mg/kg-bw ; sublethal effects : dose-dependent increase in sedation, dyspnea, exophthalmos, curved position, trismus, tonic-clonic muscle spasms, and ruffled fur ; surviving animrecovered within 3 to 5 days) Practically non-toxic 
22 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Mammalian acute oral 

S-Metolachlor Rat 

(Rattus norvegicus) 

Combined sexes LD50 = 3267 mg/kg-bw 

Male LD50 = 2577 mg/kg-bw 

Female LD50 = 2672 mg/kg-bw 

Practically n0n-toxic 

Mammalian acute inhalation 

Metolachlor Rat 

(Rattus norvegicus) 

LC50 > 1.75 mg/L 

Mammalian reproduction (chronic) 

Metolachlor Rat 

(Rattus norvegicus) 

NOAEC = 300 mg a.i./kg-diet (based on reduced pup weights in F1 and F2 litters) 

Acute contact with adult honey bees: single dose, 48-hour observation 

Metolachlor (97) 

Adult honey bee (Apis mellifera)

LD50 > 110 μg a.i./bee (nom) 

NOAEL = 110 μg a.i./bee (nom) (no control mortality ; 0-5% mortality across 4 treatment concentrations) Practically non-toxic 

Acute oral with adult honey bee, limit: single dose, 72-hour observation 

S-Metolachlor (98.5) 

Adult honey bee (Apis mellifera) 

LD50 > 85 μg a.i./bee (nom) 

NOAEL = 85 μg a.i./bee (nom) (3% control mortality ; 3-10% mortality across 9 treatment levels) Practically non-toxic 

Acute oral with honey bee larvae 

NA Larval honey bee No data 

Chronic oral with honey bee adults 

NA Adult honey bee No data 

Chronic oral with honey bee larvae 

NA Larval honey bee No data 

Terrestrial plant seedling emergence: 21 days 

S-Metolachlor technical (97.6) 

Most sensitive monocot: Ryegrass 

EC25 = 0.0048 lb a.i./A 

NOAEC = 0.0010 lb a.i./A (based on phytotoxicity) 

Most sensitive dicot: Lettuce 

EC25 (95% C.I.) = 0.0057 (0.0011-0.0308) lb a.i./A 

NOAEC = 0.0003 lb a.i./A  (based on dry weight) 

Terrestrial plant vegetative vigor: 21 days 

Metolachlor technical (97.3) 

Most sensitive monocot: Ryegrass 

EC25 = 0.016 lb a.i./A 

NOAEC = 0.0031 lb a.i./A  (based on dry weight) 
23 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

 Most sensitive dicot: 

Cucumber 

EC25 (95% C.I.) = 0.030 (0.020-0.046) lb a.i./A 

NOAEC = 0.025 lb a.i./A  (based on dry weight) 

Freshwater fish acute: 96 hours, static 

S-Metolachlor technical (Not reported) 

Bluegill sunfish (Lepomis macrochirus) 

LC50 (95% C.I.) = 3.2 (2.8-4.6) mg a.i./L (im) 

Probit slope (95% C.I.) = 14.8 (2.1-27.5) NOAEC = 1.5 mg a.i./L (im) LOAEC = 2.59 mg a.i./L (im) (NOAEC based on no mortality or sublethal effects at ≤1.5 mg/L; swimming on surface at ≥3.29 mg/L) Moderately toxic 

Freshwater fish acute: 96 hours 

Metolachlor technical (NS) 

Rainbow trout (Salmo gairdneri) 

LC50 (95% C.I.) = 3.80 (3.37-4.27) mg/L (nom) 

NOAEC: Not specified (no mortality at ≤2.8 mg/L; mortality at ≥4.1 mg/L) Moderately toxic 

Freshwater fish early life stage: 30+ days, flow-through 

S-Metolachlor technical (98.6) 

Fathead minnow (Pimephales promelas) 

NOAEC = 0.030 mg a.i./L (mm) LOAEC = 0.056 mg a.i./L (mm) (based on most sensitive endpoint of dry weight; length also affected) 

Estuarine/marine fish acute: 96 hours, flow through 

Metolachlor technical (97) 

Sheepshead Minnow (Cyprinodon variegatus) 

LC50 (95% C.I.) = 7.9 (4.4-∞) mg/L (mm) 

NOAEC: Not specified (no mortality at ≤4.4 mg/L; 70% mortality at 9.4 mg/L) Moderately toxic 

Estuarine/marine fish early life stage (chronic): 26 days, flow through 

Metolachlor technical (97) 

Sheepshead Minnow (Cyprinodon variegatus) 

NOAEC = 1.0 mg/L (mm) LOAEC = 2.2 mg/L (mm) (NOAEC based on most sensitive endpoint of reduced lengthsurvival and hatch also affected) 

Freshwater invertebrate acute: 48 hours, static 

Metolachlor (Not reported) 

Water flea (Ceriodaphnia dubia) 

EC50 (95% C.I.) = 1.1 (0.9-1.4) mg/L 

Moderately toxic 

Freshwater invertebrate life cycle: 21 days, static renewal 

Metolachlor (Not reported) 

Water flea (Daphnia magna) 

NOAEC = 0.001 mg/L (nom) LOAEC = 0.01 mg/L (nom) (based on number of young per female) 
24 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Estuarine/marine invertebrate acute: 96 hours, flow through 

Metolachlor technical (97.3) 

Mysid shrimp(Mysidopsis bahia)

EC50 (95% C.I.) = 4.95 (4.21-5.94) mg a.i./L (mm) 

Probit slope (95% C.I.) = 6.1 (3.5-8.6) NOAEC = 2.3 mg a.i./L (mm) LOAEC = 4.0 mg a.i./L (mm) (NOAEC based on no mortality at ≤2.3 mg/L; surviving daphnids at 4.0 and 7.1 mg/L exhibited dark pigmentation anlethargy) Moderately toxic 

Estuarine/marine mollusc acute: 96 hours, flow through, shell deposition 

Metolachlor technical (97.3) 

Eastern oyster (Crassostrea virginica) 

EC50 (95% C.I.) = 1.6 (1.4-1.9) mg a.i./L (mm) 

NOAEC = 0.71 mg a.i./L (mm) LOAEC = 1.1 mg a.i./L (mm) (sublethal effects: reduction in feeding and fecal and pseudofecal production were observed at all observation intervals at the highest treatment level, 4.5 mg/L) Moderately toxic 

Estuarine/marine invertebrate life cycle: 28 days, flow through (chronic) 

S-Metolachlor technical 

Mysid shrimp (Mysidopsis bahia) 

NOAEC = 0.130 mg a.i./L (mm) LOAEC = 0.250 mg a.i./L (mm) (based on most sensitive endpoints of female length and dry weight; reproduction also affected) 

Benthic freshwater invertebrate 

Metolachlor Freshwater species No data 

Benthic estuarine/marine invertebrate 

Metolachlor Estuarine/marine 

species 

No data 

Aquatic vascular plant: 14 days, static 

S-Metolachlor (97.6) 

Duckweed (Lemna gibba)

EC50 (95% C.I.) = 0.021 (0.019-0.023) mg a.i./L (mm) 

NOAEC = 0.0076 mg a.i./L (mm) LOAEC = 0.018 mg a.i./L (mm) (based on most sensitive endpoint of frond number, biomass affected; sublethal effects: less root formation at ≥0.0076 mg

compared to the control; chlorosis at ≥0.018 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

S-Metolachlor (97.6) 

Green alga (Selenastrum capricornutum) 

EC50 (95% C.I.) = 0.0080 (0.0026-0.025) mg a.i./L (mm) 

NOAEC = 0.0015 mg a.i./L (mm) LOAEC = 0.0030 mg a.i./L (mm) (based on cell density; sublethal effects: bloated cells at ≥0.0mg/L; cell fragments at ≥0.0030 mg/L) 
25 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Marine diatom (Skeletonema costatum) 

EC50 (95% C.I.) = 0.061 (0.049-0.076) mg a.i./L (mm) 

NOAEC = 0.0017 mg a.i./L (mm) LOAEC = 0.0048 mg a.i./L (mm) (based on cell density; sublethal effects: cell fragments and bloated cells at ≥ 0.15 mg/L; thin cell walls at ≥ 0.56 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Freshwater diatom (Navicula pelliculosa) 

EC50 (95% C.I.) = 0.38 (0.27-0.56) mg a.i./L (mm) 

NOAEC = 0.0037 mg a.i./L (mm) LOAEC = 0.013 mg a.i./L (mm) (based on cell density; sublethal effects: bloated cells and cefragments at ≥ 0.13 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Cyanobacterium (Anabaena flos-aquae) 

EC50 (95% C.I.) = 1.2 (0.9-1.6) mg a.i./L (mm) 

NOAEC = 0.063 mg a.i./L (mm) LOAEC = 0.19 mg a.i./L (mm) (based on cell density; cell fragments at ≥0.72 mg/L; bloated 

cells at 6.8 mg/L) 

Abbreviations: C.I. = confidence interval; form. = formulation; im = initial measured; mm = mean measured; nom = nominal; NA = nospecified; TEP = typical end-use product; TWA = time-weighted average 
26 

Table 6-3. Summary of Most Sensitive Endpoints from Toxicity Studies with Degradates of Metolachlor: 

(CGA-354743) and Metalochlor-OA (CGA-51202) 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Terrestrial invertebrate: 14 days 

Metolachlor-ESA  (92) 

Earthworm (Eisenia foetida) 

LC50 > 920 mg a.i./kg-dry soil (nom) 

NOAEC = 920 mg a.i./kg-dry soil (nom) 

Terrestrial plant seedling emergence: Tier I, 21 days 

Metolachlor-ESA  (92) 

Most sensitive monocot: Ryegrass 

EC25 < 0.5 lb a.i./A 

NOAEC < 0.5 lb a.i./A (based on dry weight) 

Most sensitive dicot: Tomato, carrot 

EC25 > 0.5 lb a.i./A 

NOAEC < 0.5 lb a.i./A (NOAEC based on emergence and dry weight for tomato ancarrot, respectively) 

Terrestrial plant vegetative vigor: Tier I, 21 days 

Metolachlor-ESA (92) 

Most sensitive monocot: None 

EC25 > 0.5 lb a.i./A 

NOAEC = 0.5 lb a.i./A 

Most sensitive dicot: None 

EC25 > 0.5 lb a.i./A 

NOAEC = 0.5 lb a.i./A 

Terrestrial plant seedling emergence: Tier I, 21 days 

Metolachlor-OA  (99.9) 

Most sensitive monocot: Onion 

EC25 > 0.5 lb a.i./A 

NOAEC < 0.5 lb a.i./A (NOAEC based on emergence) 

Most sensitive dicot: None 

EC25 > 0.5 lb a.i./A 

NOAEC = 0.5 lb a.i./A (NOAEC based on dry weight and length, respectively) 

Terrestrial plant vegetative vigor: Tier I, 21 days 

Metolachlor-OA (99.9) 

Most sensitive monocot: None 

EC25 > 0.5 lb a.i./A 

NOAEC = 0.5 lb a.i./A 

Most sensitive dicot: None 

EC25 > 0.5 lb a.i./A 

NOAEC = 0.5 lb a.i./A 

Freshwater fish acute: 96 hours, static 

Metolachlor-ESA (95) 

Rainbow trout (Oncorhynchus mykiss) 

LC50 (95% C.I.) = 48 (36-64) mg a.i./L (mm) 

NOAEC = 36 mg a.i./L (mm) LOAEC = 64 mg a.i./L (mm) (NOAEC based on no mortality and sublethal effects at ≤36 

mg/L; sublethal effects: erratic swimming, loss of equilibriuand pigmentation changes at 64 and 112 mg/L) Slightly toxic 
27 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Freshwater fish acute: 96 hours, static 

Metolachlor-OA (Not reported) 

Rainbow trout (Oncorhynchus mykiss) 

LC50 > 96.3 mg/L (mm) 

NOAEC = 96.3 mg/L (mm) Practically non-toxic 

Freshwater fish acute: 96 hours, static 

Metolachlor-OA (Not reported) 

Crucian carp (Cyprinus carpio) 

LC50 > 93.1 mg a.i./L (mm) 

NOAEC = 931. Mg a.i./L (mm) Practically nontoxic 

Freshwater invertebrate: 48 hours, static 

Metolachlor-ESA (95) 

Water flea (Daphnia magna) 

LC50 > 108 mg a.i./L (mm) 

NOAEC = 108 mg a.i./L (mm) (no treatment-related mortality or sublethal effects) Practically non-toxic 

Freshwater invertebrate acute: 48 hours, static 

Metolachlor-OA (Not reported) 

Water flea (Daphnia magna) 

EC50 (95% C.I.) = 15.4 (13.0-18.4) mg a.i./L (mm) 

Probit slop (95% C.I.) = 6.1 (3.8-8.4) NOAEC = 5.2 mg a.i./L (mm) LOAEC = 9.05 mg a.i./L (mm) (NOAEC based no mortality at 5.2 mg/L) Slightly toxic 

Aquatic vascular plant: 14 days, static 

Metolachlor-ESA (99) 

Duckweed (Lemna gibba)

7-day EC50 (95% C.I.) = 43 (30-61) mg a.i./L (im) 

7-day EC05 = 4.0 mg a.i./L (im) 7-day NOAEC < 6.1 mg a.i./L (im) 7-day LOAEC = 6.1 mg a.i./L (im) (based on frond number; sublethal effects: small and shrivel≥24 mg/L; chlorosis of half of fronds at 98 mg/L) Note: Since the NOAEC is non-definitive (i.e., NOAEC < lo

test concentration), the EC05 will be used for assessing risk t

listed species. 

Aquatic vascular plant: 14 days, static 

Metolachlor-OA (>99.9) 

Duckweed (Lemna gibba)

EC50 > 95.4 mg a.i./L (im) 

NOAEC = 95.4 mg a.i./L (im) 
28 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Aquatic nonvascular plant: 72 hours, static 

Metolachlor-ESA (99.9) 

Green alga (Selenastrum capricornutum)

EC50 > 99.45 mg a.i./L (mm) 

NOAEC = 99.45 mg a.i./L (mm) (based on cell density) 

Aquatic nonvascular plant: 72 hours, static 

Metolachlor-OA (Not reported) 

Green alga (Scenedesmus subspicatus) 

EC50 (95% C.I.) = 57.1 (29.3-∞) mg/L (im) 

NOAEC = 29.3 mg/L (im) LOAEC = 92.2 mg/L (im) (based on cell density) 

Abbreviations: C.I. = confidence interval; form. = formulation; im = initial measured; mm = mean measured; nom = nominal; NA = nospecified; TEP = typical end-use product; TWA = time-weighted average 
29 

6.3 Ecological Incidents 

A preliminary review on June 27, 2014 of the Ecological Incident Information System (EIIS, 

version 2.1.1), which is maintained by the Agency’s Office of Pesticide Programs, and the Avian 

Monitoring Information System (AIMS), which is maintained by the American Bird 

Conservancy, indicates a total of 269 reported ecological incidents associated with the use of 

metolachlor and 206 reported ecological incidents associated with the use of S-metolachlor. This 

total excludes incidents classified as ‘unlikely’ or ‘unrelated’ and only includes those incidents 

with certainty categories of ‘possible’, ‘probable’, and ‘highly probable’ (for EIIS) and 

‘possible’, ‘probable’, ‘likely’, ‘highly likely’ and ‘certain’ (for AIMS). Incidents classified as 

‘unlikely’ the result of or ‘unrelated’ to metolachlor or S-metolachlor will not be included in this 

Problem Formulation or the ecological risk assessment conducted for Registration Review. 

All of the metolachlor incidents, excluding those classified as ‘unlikely’ or ‘unrelated’, occurred 

between 1984 and 2014. Thirteen of the metolachlor incidents reported in the EIIS database 

involved aquatic animals, 2 involved terrestrial animals, and 254 involved plants. The certainty 

categories regarding the likelihood that the use of metolachlor caused the 269 incidents were 

probable (99 incidents), possible (167 incidents), and highly probable (3 incidents). One hundred 

and sixty-seven of the incidents were considered registered uses at the time of the incident, 17 

involved misuses, and the legality of use was undetermined in 85 incidents. The reported 

incidents for metolachlor involved 265 uses that are currently registered [agriculture area, corn, 

nut, peanut, potato, soybean, turf, and wheat], and 4 in which the use site was not specified. 

Incidents are reported separately for S-metolachlor, but the number and type of reports are 

similar. There were a total of 206 reported incidents for S-metolachlor. Twenty-nine involved 

terrestrial animals and 177 involved plants. Of the 29 incidents that involved terrestrial animals, 

only 1 was a bird incident also reported in AIMS (EIIS: 1015105). The certainty categories 

regarding the likelihood that the use of S-metolachlor caused the 206 incidents were probable (74 

incidents) and possible (132 incidents). One hundred and forty-two of the incidents were 

considered registered uses at the time of the incident, 7 involved misuses, and the legality of use 

was undetermined in 57 incidents. Based on the data, it appears that most of the reports are 

undesired effects treatment site, when applied in accordance with a registered use. The most 

commonly reported crops damaged were corn, cotton, and soybean. 

In addition to the incidents recorded in EIIS and AIMS, additional incidents have been reported 

to the Agency in aggregated incident reports. Pesticide registrants report certain types of 

incidents to the Agency as aggregate counts of incidents occurring per product per quarter. 

Ecological incidents reported in aggregate reports include those categorized as ‘minor fish and 

wildlife’ (W-B), ‘minor plant’ (P-B), and ‘other non-target’ (ONT) incidents. ‘Other non-target’ 

incidents include reports of adverse effects to insects and other terrestrial invertebrates. For 

metolachlor, registrants have reported 5 minor fish and wildlife incidents, 44 minor plant 

incidents, and 0 other non-target incidents. For S-metolachlor, registrants have reported 4 minor 

fish and wildlife incidents, 672 minor plant incidents, and 0 other non-target incidents. Unless 

additional information on these aggregated incidents becomes available, they will be assumed to 

be representative of registered uses of metolachlor and S-metolachlor in the risk assessment. 
30 

In the risk assessment, the incidents will be further evaluated to determine if the reported 

incidents represent current patterns of use for metolachlor and S-metolachlor. Examples of 

additional considerations are mitigation (e.g., reduced application rates), product cancellations, 

and changes in use patterns that have occurred since the date of the reported incident(s). 

7 Exposure Pathways of Concern 

The environmental fate properties and use patterns of metolachlor/S-metolachlor indicate that 

direct spray, spray drift, leaching to ground water, atmospheric deposition, and runoff represent 

potential transport mechanisms of metolachlor/S-metolachlor to aquatic and terrestrial 

organisms. Drinking water and inhalation exposure pathways were screened using the SIP 

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

methods, respectively. Inhalation was found to be an exposure pathway of low concern (no LOC 

exceedances are expected; Appendix E). Results of SIP (Appendix E) indicate that drinking 

water could be an exposure pathway of concern for birds (acute and chronic exposure) and 

mammals (chronic exposure). SIP and STIR are described in detail at: 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm. 

8 Analysis Plan 

8.1 Stressors of Concern 

8.1.1 Ecological Risk Assessment 

Although degradates metolachlor-ESA and metolachlor-OA are less toxic than parent 

metolachlor/S-metolachlor, they are more persistent and are formed to a significant extent in fate 

studies and are often detected in monitoring studies. Therefore, the stressors of concern for 

aquatic and terrestrial organisms are metolachlor/S-metolachlor and degradates metolachlor-ESA 

and metolachlor-OA. Similar to assessments in the past, risk to non-target organisms will be 

assessed separately for metolachlor/S-metolachlor, metolachlor-ESA, and metolachlor-OA. 

8.1.2 Drinking Water Exposure Assessment 

The drinking water assessments conducted to support the Registration Review human health risk 

assessments of metolachlor/S-metolachlor will incorporate modeled estimates of parent 

compounds metolachlor/S-metolachlor and degradate residues of concern in surface and ground 

waters. The metolachlor/S-metolachlor residues of concern may be reevaluated pending receipt 

and review of additional environmental fate and toxicity data for metolachlor/S-metolachlor and 

its degradates. Following the recommendation of the Residues of Concern Knowledgebase 

Subcommittee (ROCKS), parent metolachlor, CGA-51202 (metolachlor-OA), CGA-40172, and 

CGA-50720 will be assessed together in the drinking water assessment using a total toxic 

residues (TTR) approach and will follow the latest guidance and methodology (USEPA, 2014c, 

D424250). 

8.2 Measures of Exposure 
31 

EFED will use standard available models to evaluate potential exposures to aquatic and 

terrestrial organisms as described at http://www.epa.gov/pesticides/science/models_db.htm. 

8.2.1 Available Monitoring Data 

The Agency is aware of monitoring conducted by federal and state agencies and this information 

will be considered in the assessment to the extent that data on metolachlor are available. 

8.3 Measures of Effect 

Toxicity data presented in Section 6 of this problem formulation will be used to calculate risk 

quotients. Any additional information submitted by the registrant or found in the open literature 

prior to conducting the risk assessment will also be considered. The open literature studies are 

identified using EPA’s ECOTOXicology database (ECOTOX)2

, which employs a literature 

search engine for locating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. 

The evaluation of both sources of data can also provide insight into the direct and indirect effects 

of pesticides on biotic communities from loss of species that are sensitive to the chemicals and 

from changes in structure and functional characteristics of the affected communities. 

9 Endangered Species Assessments 

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to federally listed threatened and/or endangered (listed) species from 

registered uses of pesticides in Registration Review. The process for evaluating potential risks to 

listed species is further described at 

http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm. 

10 Endocrine Disruptors Screening Program 

Metolachlor was included in the first group of 67 chemicals issued an order to conduct Tier 1 

EDSP testing. For additional information the EDSP program, visit http://www.epa.gov/endo/. 

11 Preliminary Identification of Data Gaps 

11.1 Environmental Fate 

Table 11-1 identifies environmental fate studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether or not further data are needed in order 

to support risk assessment. 

 

2 http://cfpub.epa.gov/ecotox/
32 

Table 11-1. Environmental Fate Data for Metolachlor/S-Metolachlor 

OCSPP 

Guideline 

Data Requirement Submitted 

Studies 

(MRID) 

Study 

Classification 

Data 

Gap? 

Comments 

835.2120 Hydrolysis 40430201 Acceptable No -- 

835.2240 Aqueous Photolysis 40430202 Acceptable No -- 

835.2410 Soil Photolysis 43928935 Supplemental No -- 

835.4100 Aerobic Soil 

Metabolism 

41309801A-B Acceptable 

Yes 

(Partially 

Fulfilled)

The aerobic soil metabolism 

study was conducted with two 

soils. Data are required under 

40 CFR Part 158. OCSPP 

guidance recommends that 

these studies be performed 

with four soils. Two 

additional soils are needed to 

fulfill the data requirement. 

45499606 Supplemental 

43928936 Supplemental 

835.4200 Anaerobic Soil 

Metabolism 41309801A-B Acceptable 

Yes 

(Partially 

Fulfilled)

The anaerobic soil metabolism

study was conducted with 

only one soil. Data are 

required under 40 CFR Part 

158. OCSPP guidance 

recommends that these studies 

be performed with four soils. 

Three additional soils are 

needed to fulfill the data 

requirement. 

835.4300 Aerobic Aquatic 

Metabolism 41185701 Acceptable 

Yes 

(Partially 

Fulfilled)

The aerobic aquatic 

metabolism study was 

conducted with only one 

sediment –water system. Data 

are required under 40 CFR 

Part 158. OCSPP guidance 

recommends that these studies

be performed with two 

sediment-water systems. . 

One additional sedimentwater system is needed to 

fulfill the data requirement. 

835.4400 Anaerobic Aquatic 

Metabolism 41185701 Acceptable 

Yes 

(Partially 

Fulfilled)

The anaerobic aquatic 

metabolism study was 

conducted with only one 

sediment –water system. Data 

are required under 40 CFR 

Part 158. OCSPP guidance 

recommends that these studies

be performed with two 

sediment-water systems. . 

One additional sedimentwater system is needed to 

fulfill the data requirement. 
33 

OCSPP 

Guideline 

Data Requirement Submitted 

Studies 

(MRID) 

Study 

Classification 

Data 

Gap? 

Comments 

835.1230 

835.1240 

Adsorption/ desorption

and leaching 

43928937 Acceptable* No -- 

40494602 

40494603 

40494604 

40494605 

Acceptable No 

-- 

835.1410 Volatility – laboratory 40494606 Acceptable No -- 

835.6100 Terrestrial Field 

Dissipation (TFD) 

45848001 Supplemental* No -- 

41335701 

41484203 

(amendment) 

Supplemental No -- 

41335702 

41484204 

(amendment) 

Supplemental No -- 

41309802 

41484201 

(amendment) 

Supplemental No -- 

 41309803 

 41484202 

(amendment) 

Supplemental No -- 

 41309804 

 41484205 

(amendment) 

Supplemental No -- 

 41309805 

 41484206 

(amendment) 

Supplemental No -- 

835-7100 Groundwater 

Monitoring 

47017401 

47017402 

47017403 

47017404 

Acceptable No -- 

850.7100 

Environmental 

chemistry method 

(ECM/ILV) in soil 

-- -- Yes 

ECM/ILV in soil for 

metolachlor/S-metolachlor is 

outstanding 

Environmental 

chemistry method 

(ECM) in water 

45499611 Supplemental* No -- 

45499612 Supplemental** No -- 

(ILV) in Water -- -- Yes 

ILV in water for 

metolachlor/S-metolachlor is 

outstanding 

850.1730 Fish Bioconcentration 41154201 Acceptable No -- 

* Study using S-metolachlor (CGA 77102). 

** Study using metolachlor. 

11.2 Ecological Effects 

Table 11-2 identifies ecological effects studies by MRID that offer data for each guideline 

requirement, as well as study classifications and whether or not further data are needed in order 

to support risk assessment. Rationale for the additional data requested is presented below the 

tables. 
34 

Table 11-2. Ecological Effects Data for Metolachlor, S-Metolachlor, Metolachlor-OA, and Metolachlor-ES

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data 

Avian Testing 850.2100 Avian oral 

toxicity 

Metolachlor 00015547 

00062465 (waterfowl) 

Supplemental Acceptable 

No Acute oral toxicity data for a p

required under the new 40 CFR not been submitted for this data metolachlor or S-metolachlor. A guideline-compliant passerinneeded. The sublethal effect oobserved in a study with bobwmetolachlor. Passerine birds mpathways that are different from therefore be more sensitive to mpasserines exhibit behavioral redosing that are potential indicathe field (e.g., regurgitation of when direct biochemically-medapparent. In the absence of these data, pasurrogate pesticides – starting wrelated pesticides (e.g., chloroa

proceeding to data for less relaused to characterize the acute tpasserine species.

S-Metolachlor 43928906 

(waterfowl) 

Acceptable No 

43928907 (upland game) 

Acceptable 

Metolachlor S-Metolachlor 

No data (passerine species) 

NA Yes 

850.2200 Avian dietary 

toxicity 

Metolachlor 44015602 

(waterfowl) 

Acceptable No -- 

46508901 (upland game) 

Acceptable 

S-Metolachlor 43928909 

(waterfowl) 

Acceptable No -- 

43928908 (upland game) 

Acceptable 
35 

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data 

850.2300 Avian 

reproduction 

Metolachlor 46070102 

(upland game) 

Acceptable No -- 

46070101 (waterfowl) 

Acceptable 

S-metolachlor 44995901 

(upland game) 

Acceptable No Avian data for the reproductive 

waterfowl will be bridged to S-

(waterfowl) No data 

Insect Pollinator Testing 850.3020 Honey bee 

acute contact toxicity 

Metolachlor 44718401 Acceptable No -- 

S-Metolachlor 44718402 Acceptable No -- 

Special Study (OECD 213) 

Honey bee adult acute oral toxicity 

Metolachlor 44718401 Acceptable No -- 

S-Metolachlor 44718402 Acceptable No -- 

Special Study (OECD 237) 

Honey bee larvae acute and chronic oral toxicity 

Metolachlor S-Metolachlor 

No data NA Yes Guidance for assessing pesticid

2014a) describes a screening-leassessment process that includeand chronic oral toxicity tests wand chronic oral toxicity tests woral toxicity data for adult bees oral toxicity data for bee larvae 

metolachlor or S-metolachlor. In the absence of these data, hofor surrogate pesticides – startirelated pesticides (e.g., chloroa

proceeding to data for less relaused to characterize the oral tometolachlor to honey bees. Per the guidance (USEPA, 201field/pollen and nectar residue) 

Special Study 

Honey bee adult chronic oral toxicity 

Metolachlor S-Metolachlor 

No data NA Yes 

Special Study 

Pollinator pollen and nectar residue studies 

Metolachlor S-Metolachlor 

No data NA Need for data 

contingent upon results of Tier 1 bee studies 

850.3040 Semi-field and 

field testing for pollinators 

Metolachlor S-Metolachlor 

No data NA Need for data 

contingent upon results of Tier 1 bee studies 
36 

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data studies may be needed, contingTier 1 studies. 

Aquatic Organisms Testing850.1010 Freshwater 

invertebrate acute toxicity 

Metolachlor 00015546 Acceptable No -- 

S-Metolachlor 43928912 Acceptable No -- Metolachlor-ESA 44931703 Acceptable No -- Metolachlor-OA 44929503 Supplemental No Although the submitted study w

as Supplemental due to not re

purity, it is sufficient for quantecological risk assessment. 

850.1025 850.1035 850.1045 850.1055 

Saltwater invertebrate acute toxicity 

 Metolachlor 43487103 

(shrimp) 

Acceptable No -- 

42378901 (mollusc) 

Acceptable 

S-Metolachlor No data 

(shrimp) 

NA No Mysid and Eastern oyster acute 

metolachlor will be bridged to 

No data (mollusc) 

NA 

850.1075 Freshwater 

fish acute toxicity 

Metolachlor 00015534 

00018723 (warm water) 

Acceptable/ Supplemental (depending on species) Acceptable 

No -- 

00018722 (cold water) 

Acceptable 

S-Metolachlor 43928910 

(warm water) 

Acceptable No -- 

43928911 (cold water) 

Acceptable 

Metolachlor-ESA 44931702 Supplemental No Although the submitted study w

classified as Supplemental duis sufficient for quantitative usassessment. 

Metolachlor-OA 44929501 

44929502 

Supplemental Supplemental 

No Although the submitted studies 

crucian carp are classified as S
37 

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data reporting the test material puritdeviations, they are sufficient fecological risk assessment. 

850.1075 Saltwater fish 

acute toxicity 

Metolachlor 43487101 

43044602 

Acceptable Supplemental 

No -- 

S-Metolachlor 46829506 Acceptable No -- 

850.1300 Freshwater 

invertebrate life cycle 

Metolachlor 46322101 

43802601 

Acceptable Supplemental 

No -- 

S-Metolachlor 46829507 Acceptable No -- 

850.1350 Saltwater 

invertebrates life cycle 

Metolachlor No data NA No Mysid chronic toxicity data for 

bridged to metolachlor. 

S-Metolachlor 44995902 Acceptable No -- 

850.1400 Freshwater 

fish early life stage 

Metolachlor No data NA No Freshwater fish chronic toxicit

will be bridged to metolachlor. 

S-Metolachlor 44995903 Acceptable No -- 

850.1400 Saltwater fish 

early life stage 

Metolachlor 43044602 Supplemental No Although the submitted study w

is classified as Supplemental ddeviations, it is sufficient for qecological risk assessment. 

S-Metolachlor No data NA No Estuarine/marine fish chronic t

metolachlor will be bridged to 

NonGuideline Whole sediment: 

chronic invertebrates, freshwater and marine 

Metolachlor S-Metolachlor 

No data NA Yes Chronic sediment invertebrate 

under 40 CFR Part 158 if: 

i. the estimated environme

in sediment is > 0.1 of t

ii.the half-life of the pestic

days in either the aerobimetabolism studies and exist: A. The soil partition co

B. The log Kow is ≥ 3C. The Koc is ≥ 1,000

The half-life of metolachlor/S-metabolism and aerobic aquati
38 

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data 49 and 141 days, respectively; metolachlor/S-metolachlor 3.0Modeling via the Surface WateCalculator (SWCC, v. 1.106)a i

pore water EECs of up to 41.9 respectively. Although the peaconcentration is approximately 

μg/L for D. magna (E067777), 

EEC is 41 * NOAEC of 1 μg/L According to toxicity testing anassessment guidance for benthi2014b), if the 21-day pore watewater column NOAEC, the neetoxicity testing is indicated. Therefore, chronic sediment teChironomus dilutus, freshwateazteca, and/or estuarine/marine plumulosus are needed. A tieredata from sub-chronic (10-day) with the three species may be uspecies should undergo chronic In the absence of these data, seinvertebrate chronic toxicity da– starting with data for closely chloroacetamides) and proceedpesticides – may be used to chatoxicity of propargite to sedime

Nontarget area phytotoxicity testing 850.4100 Seedling 

emergence and seedling growth 

Metolachlor 43487107 Acceptable No -- 

S-Metolachlor 43928932 Supplemental Yes The submitted study was classi

to only testing 6 species instead species. Testing with an additidicots, one of which is soybean
39 

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data 

MetolachlorESA 44931718 Supplemental Yes The submitted study was classi

to not establishing NOAECs focarrot. A study that defines a Nconcentration that is not statistnegative control for all assesse

Metolachlor-OA 44929513 Supplemental Yes The submitted study was classi

to not establishing a NOAEC fdefines a NOAEC (i.e., a concestatistically different from the nassessed endpoints) is needed. 

850.4150 Vegetative 

vigor 

Metolachlor 43487108 Acceptable No -- 

S-Metolachlor 43928933 Supplemental Yes The submitted study was classi

to only testing 6 species instead species. Testing with an additidicots, one of which is soybean

Metolachlor-ESA 44931718 Acceptable No -- Metolachlor-OA 44929513 Acceptable No -- 

850.4400 Aquatic plant 

toxicity test using Lemna

spp. 

Metolachlor 43487105 Acceptable No -- 

S-Metolachlor 43487105 Acceptable No -- Metolachlor-ESA 44931720 Acceptable No -- Metolachlor-OA 44929514 Acceptable No -- 

850.4500 Algal toxicity Metolachlor 43541301 

(green alga) 

Acceptable No -- 

43541302 (freshwater diatom) 

Acceptable 

43487106 (marine diatom) 

Acceptable 

S-Metolachlor 43928929 

(green alga) 

Acceptable No -- 
40 

OCSPP Guideline 

Data Requirement 

Chemical Submitted 

Study (MRID) 

Classification Are data needed 

to conduct the risk assessment? 

Justification and AssumptionAbsence of Data 

46829509 (freshwater diatom) 

Acceptable 

43928930 (marine diatom) 

Acceptable 

Metolachlor-ESA Supplemental 

(green alga) 

Supplemental No Although the submitted study w

classified as Supplemental duis sufficient for quantitative usassessment. 

Metolachlor-OA 44929515 

(green alga) 

Supplemental No Although the submitted study w

classified as Supplemental du(72 hours instead of 96 hours) material not being reported, it iquantitative use in the ecologic

850.4550 Cyanobacteria 

toxicity 

Metolachlor 43487104 Acceptable No -- 

S-Metolachlor 46829510 Acceptable No -- 

Abbreviations: NA = not applicablea CA Lettuce STD; 1 application @ 1.3 lb a.i./A 
41 

Study Title: Adult honey bee chronic oral toxicity

Rationale for Requiring the Data

Terrestrial invertebrate chronic toxicity data are required for metolachlor/S-metolachlor to 

quantitatively assess the potential effects on this group of organisms. Bees can be exposed 

through multiple pathways including contact with sprays and through ingestion of residues in 

food/water (e.g., pollen/nectar and water used to maintain colony temperature). Worker bees 

foraging on flowers for pollen and nectar can be repeatedly exposed to residues in pollen and 

nectar either through direct contamination of these matrices by foliar sprays or through 

translocation of residues via systemic transport of s-metolachlor/metolachlor. Residues can in 

turn be brought back to bee colonies where in-hive bees including young adult and 

developing brood (i.e., eggs, larvae and pupae) may be exposed. Honey bees are a surrogate 

for all terrestrial invertebrates. 

This is a non-guideline study; an OECD protocol is under development. A protocol should be 

submitted to the Agency for review before commencing the study and should include 

provisions for measuring the concentration of metolachlor/S-metolachlor in the actual diet of 

the honey bee. 

Practical Utility of the Data 

How will the data be used? 

The 10-day toxicity study with young adult bees provides no-observed adverse effect level 

(NOAEL) and lowest-observed adverse effect level (LOAEL) for assessing chronic effects. 

Data obtained from this study will be used in estimating chronic risk from metolachlor/Smetolachlor to individual adult bees, which will be used as a surrogate for all terrestrial 

invertebrates. The data will reduce uncertainties associated with the registration review risk 

assessment for terrestrial invertebrates and will improve EPA’s understanding of the potential 

effects of s-metolachlor/metolachlor on terrestrial species. If honey bee chronic adult data are 

not submitted, risks to terrestrial invertebrates from chronic exposure to metolachlor/Smetolachlor will be assumed. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency 

would have to assume that s-metolachlor/metolachlor "may affect" endangered terrestrial 

invertebrates directly (and endangered species from other taxa indirectly), and use of 

metolachlor/S-metolachlor might need to be restricted in areas where endangered species 

could be exposed. The lack of these data will limit the flexibility the Agency and registrants 

have in coming into compliance with the Endangered Species Act and could result in use 

restrictions for s-metolachlor/metolachlor which are unnecessarily severe. 

 
42 

Study Title: Larval honey bee acute and chronic oral toxicity

Rationale for Requiring the Data

Terrestrial invertebrate chronic toxicity data are required for metolachlor/S-metolachlor to quantitatively 

assess the potential effects on this group of organisms. Developing bee brood (i.e., larvae and pupae) can 

be exposed to metolachlor/S-metolachlor through residues brought back to the colony by worker bees 

foraging in areas where the pesticide has been applied. While larvae are typically fed royal or brood jelly 

during their early stages of development, worker bee (females) and drone (males) larvae are also fed 

pollen/honey (bee bread) directly by in-hive nurse bees. Honey bees are a surrogate for all terrestrial 

invertebrates. 

This is a non-guideline study; a 21-day larval toxicity study is under development by OECD and provides 

both acute and chronic toxicity data on developing bee brood. Alternatively, a separate acute (single dose) 

larval toxicity study following OECD Guideline 237 as well as the 21-day repeat dose chronic toxicity 

study can be submitted to address both acute and chronic larval endpoints. A protocol for the 21-day larval 

toxicity test should be submitted to the Agency for review before commencing the study and should 

include provisions for measuring the concentration of s-metolachlor/metolachlor in the actual diet of the 

honeybee. 

Draft guidance for the 21-day larval toxicity study is available at: 

http://www.oecd.org/env/ehs/testing/Draft_GD_honeybees_rep_exp_for_2nd_CR_25_November_2013.pdf

Practical Utility of the Data 

How will the data be used? 

Acute (LD50) and chronic (NOAEL/LOAEL) toxicity data on developing bee brood will be used to 

determine the effects on survival and development (adult bee emergence) from repeat exposures to 

metolachlor/S-metolachlor. Data obtained from this study will be used in estimating risk to individual 

brood bees, which will be used as a surrogate for all terrestrial invertebrates. The data will reduce 

uncertainties associated with the registration review risk assessment for terrestrial invertebrates and will 

improve EPA’s understanding of the potential effects of metolachlor/S-metolachlor on terrestrial 

species. If honey bee larval data are not submitted, risks to larval terrestrial invertebrates from acute and 

chronic exposure to s-metolachlor/metolachlor will be assumed. 

How could the data impact the Agency’s future decision-making? 

If future endangered species risk assessments are performed without these data, the Agency would have to 

assume that metolachlor/S-metolachlor "may affect" endangered terrestrial invertebrates directly (and 

endangered species from other taxa indirectly), and use of metolachlor/S-metolachlor might need to be 

restricted in areas where endangered species could be exposed. The lack of these data will limit the 

flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act 

and could result in use restrictions for s-metolachlor/metolachlor which are unnecessarily severe. 

 
43 

Study Title: Residue analysis of nectar and pollen in flowering crops 

Rationale for Requiring the Data 

Measured residues in pollen and nectar can serve as a means through which screening-level risk quotients 

may be refined. Initially, risk estimates are based on exposure values generated using conservative models or 

default values. However, risk estimates can be refined using measured residue values in pollen and/or nectar 

collected by bees. Such data may be available through modifications to existing guideline studies identified 

for residue chemistry, including the magnitude of residue crop trial (OCSPP 860.1500[2]) and through field 

rotational crop trials (OCSPP 860.1900[3]). Table 2 depicts selected test requirements from the 40CFR 

Part158 Subpart O (Residue Chemistry §158.1410). 

Table 2. Recommendations for Residue Data Requirements.

Number Study Type 

Use Pattern 

Test 

substance

Test 

Note 

No. 

Terrestrial 

Food or 

Feed

Aquatic 

Food 

Greenhouse 

Food 

Indoor 

Food

Residential 

Outdoor 

Magnitude of residue 

860.1500 Crop field 

trials R R R CR CR TEP 

860.1900 

Field 

rotational 

crops 

CR CR NR NR NT TEP 

Alternatively, data on residues in pollen and nectar may be available through the ecological effect studies 

where pesticide is applied under semi- and full-field conditions. To support residue analysis in pollen and 

nectar, the registrant must provide evidence that suitable environmental chemistry methods (ECM) have been 

used to quantify residues. 

Practical Utility of the Data 

To assess risk to non-target listed and non-listed terrestrial invertebrate species. These data would allow the 

Agency to refine the screening level risk assessment for beneficial terrestrial invertebrates. Exposure data is 

an integral part of determining the potential for risk to beneficial terrestrial invertebrates through direct 

exposure from their food sources. 

The data EPA intends to call in are necessary to inform the determination required under FIFRA or the ESA 

as to whether continued registration of a pesticide is likely to result in unreasonable adverse effects or is not 

likely to jeopardize threatened or endangered species or its critical habitat. The lack of these data will limit 

the flexibility that the Agency and registrants have in coming into compliance with ESA and could result in 

use restrictions that are unnecessarily severe. In addition, the lack of these data may result in an uncertain 

assumed risk and potential mitigation of pyraclostrobin formulations under FIFRA. 
44 

Study Title: Chronic Freshwater Sediment Testing Flow-through: (Hyallela azteca) 

(Chironomus dilutus or C. tentans) (Chironomus riparius) (ORD Study Method EPA 600/R099-064) 

Study Title: Chronic Estuarine/Marine Sediment Testing Flow-through: (Leptocheirus 

plumulosus) (ORD Study Method EPA 600/R-099-020) 

Rationale for Requiring the Data 

Based on physiochemical properties, the metolachlor/s-metolachlor may sorb to organic materials 

in sediment and may be toxic to aquatic invertebrates that dwell in and ingest sediment. The use 

pattern, chemical properties, estimated exposure, and toxicity profile of metolachlor/s-metolachlor 

indicate need for chronic (life cycle) sediment toxicity tests to fully evaluate potential risks to 

benthic invertebrates. The 40 CFR part 158.630 requires a chronic freshwater sediment study 

when the estimated environmental concentration (EEC) in sediment is > 0.1 of the actual 

LC50/EC50 values and the half-life of the pesticide in the sediment is > 10 days and any of the 

following conditions exist: a. Kd > 50, b. the log Kow > 3, or c. the Koc > 1000. Metolachlor/smetolachlor meets these criteria. Multiple freshwater species (Chironomus dilutus or C. tentans; 

Hyalella azteca; Chironomus riparius) and/or a saltwater species (Leptocheirus plumulosus) are 

needed to account for differential sensitivity and exposure potential of benthic invertebrates to the 

pesticide active ingredient. 

Practical Utility of the Data 

How will the data be used? 

Data from sediment toxicity studies will be used to estimate potential risks to benthic organisms 

associated with the use of the pesticide active ingredient. The data will be used to reduce 

uncertainties associated with the current risk assessment for benthic invertebrates. 

How could the data impact the Agency’s future decision-making? 

The data EPA intends to call in will inform the determination required under FIFRA or the ESA as 

to whether continued registration of a pesticide is likely to result in unreasonable adverse effect 

non-target species or is not likely to jeopardize listed or endangered species or its critical 

habitat. The lack of these data will limit the flexibility that the Agency and registrants have in 

coming in to compliance with ESA and could result in significant use restrictions. In addition, the 

lack of these data may result in assumed risk and potential mitigation of metolachlor/s-metolachlor 

formulations under FIFRA.

12 References 

USEPA. 1995. Reregistration Eligibility Decision (RED). Data Package Barcode: 185152, 

172022 Metolachlor. April 1995. 

USEPA. 2002. Review of Documents Related to the Equivalency of Racemic Metolachlor 

(Metolachlor) and S-Metolachlor for Environmental Fate and Ecotoxicity. Environmental Fate 

and Effects Division, Office of Pesticide Programs. February 28, 2002. 
45 

USEPA, 2010. Drinking Water Assessment for S-Metolachlor and its Degradates 

Ethanesulfonic Acid (ESA) and Oxanilic Acid (OA) for Various Crop Uses. (DP 368735) 

April 22, 2010 

USEPA, 2010 S-metolachlor Ecological Risk Assessment to Support the IR4 Registration for 

Numerous New Uses (DP 370759) June 23, 2010. 

USEPA, 2011. FIFRA Section 18 Emergency Exemption for the Use of S-Metolachlor on 

Lettuce to Control Grass and Broadleaf Weeds Post Crop Emergence. (DP 390436) June 22, 

2011. 

USEPA, 2012. Ecological Risk Assessment for the Proposed New Uses of S-metolachlor on 

Cilantro and Garden Beet Leaves. (DP 392602) January 4, 2012 

USEPA. 2014a. Guidance for Assessing Pesticide Risks to Bees. Environmental Fate and Effects 

Division. Office of Pesticide Programs. June 23, 2014. 

USEPA. 2014b. Toxicity Testing and Ecological Risk Assessment Guidance for Benthic 

Invertebrates. Environmental Fate and Effects Division. Office of Pesticide Programs. April 10, 

2014. 

USEPA. 2014c. Metolachlor and s-metolachlor: recommended environmental degradates to 

include in drinking water assessment. Health Effects Division. Office of Pesticide Programs. 

(DP 424250) December 3, 2014. 

E067777. Foster, S., Thomas, M., and K. Wolfgang. 1998. Laboratory-derived acute toxicity of 

selected pesticides to Ceriodaphnia dubia. Australasian Journal of Ecotoxicology. 4: 53-59. 

E083887. Liu, H., Ye, W., Zhan, X., and W. Liu. 2006. A Comparative Study of Rac- and SMetolachlor Toxicity to Daphnia magna. Ecotoxicology and Environmental Safety. 63: 451-455. 

13 Bibliography 

Environmental Fate Studies (Metolachlor) 

15662 Burkhard, N. (1974) CGA-24705: Hydrolysis of CGA-24705 under Labo- ratory 

Conditions. Method no. SPR 2/74 dated Feb 27, 1974. (Unpublished study 

received Sep 26, 1974 under 5G1553; prepared by Ciba-Geigy, Ltd., submitted by 

Ciba-Geigy Corp., Greensboro, N.C.; CDL:094222-H) 

40430201 Spare, W. (1987) Determination of the Hydrolysis Rate Constants of Metolachlor: 

Agrisearch Project No. 1263. Unpublished study prepared by Agrisearch Inc. 41 

p. 
46 

16300 Aziz, S.A.; Kahrs, R.A. (1974) Photolysis of CGA-24705 in Aqueous Solution 

under Natural and Artificial Sunlight Conditions: Report No. GAAC-74041. 

(Unpublished study received Sep 26, 1974 under 5F1606; submitted by CibaGeigy Corp., Greensboro, N.C.; CDL:094385-D) 

16302 Aziz, S.A.; Kahrs, R.A. (1975) Photolysis of CGA-24705 in Aqueous Solution--

Additional Information: Report No. GAAC-75021. (Un- published study received 

on unknown date under 5F1606; submitted by Ciba-Geigy Corp., Greensboro, 

N.C.; CDL:094385-M) 

40430202 Spare, W. (1987) Determination of the Solution Photolysis Rate Con- stants and 

Photodegradation Products of Metolachlor Under Natur- al and Artificial Light: 

Laboratory Study No. 1261. Unpublished study prepared by Agrisearch Inc. 63 p. 

40519301 Spare, W.; Capps, T. (1988) Determination of the Solution Photolysis Rate 

Constants and Photodegradation Products of CGA-154281 Under Natural and 

Artificial Light: Proj. No. 1275. Unpublished study prepared by Agrisearch Inc. 

101 p. 

41210801 Spare, W.; Capps, T. (1988) Supplement To: Determination of the Solution 

Photolysis Rate Constants and Photodegradation Products of CGA-154281 Under 

Natural and Artificial Light: Project ID: MRID NO. 40519301. Unpublished study 

prepared by Agrisearch Inc. 13 p. 

16301 Aziz, S.A. (1974) Photolysis of CGA-24705 on Soil Slides under Nat- ural and 

Artificial Sunlight Conditions: Report No. GAAC-74102. (Unpublished study 

received on unknown date under 5F1606; sub- mitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:094385-J) 

40430203 Spare, W. (1987) Soil Photolysis of Metolachlor under Natural and Artificial 

Light: Laboratory Study No. 1262. Unpublished study prepared by Agrisearch 

Inc. 77 p. 

43928935 Merritt, A. (1995) Photodegradation of (carbon 14)-Metolachlor and (carbon 14)-

CGA-77102 on Soil Under Artificial Sunlight: Lab Project Number: ABR-95128: 

53-95. Unpublished study prepared by Ciba Crop Protection. 151 p. 

16296 Kaiser, F.E. (1974) Soil Degradation Study of Gba-Geigy ?sic| 14C- CGA-24705. 

(Unpublished study received Mar 27, 1975 under 5F1606; prepared by Analytical 

BioChemistry Laboratories, Inc., submitted by Ciba-Geigy Corp., Greensboro, 

N.C.; CDL:094376-N) 

153668 Bouchard, D.; Lavy, T.; Marx, D. (1982) Fate of metribuzin, meto- lachlor, and 

fluometuron in soil. Weed Science 30:629-632. 

41309801 Spare, W. (1989) Soil Metabolism of Metolachlor under Aerobic, 

Aerobic/Anaerobic, and Sterile Conditions: Lab Project Number: 1258. 

Unpublished study prepared by Agrisearch Inc. in association with Ciba-Geigy 

Corp. 130 p. 
47 

41309802 Spare, W. (1989) Soil Metabolism of Metalochlor under Aerobic, 

Aerobic/Anaerobic, and Sterile Conditions: Lab Project Number: 1258. 

Unpublished study prepared by Agrisearch, Inc. 130 p. 

43928936 Clark, A. (1995) Comparative Aerobic Soil Metabolism of Phenyl-(carbon 14)-

CGA-77102 and Phenyl-(carbon 14)-Metolachlor: Lab Project Number: ABR95102: 338-94: 12217. Unpublished study prepared by Ciba Crop Protection and 

Agrisearch, Inc. 314 p. 

44043401 Clark, A. (1995) Comparative Aerobic Soil Metabolism of Phenyl-(carbon 14)-

CGA-77102 and Phenyl-(carbon 14)-Metolachlor: Report Amendments 1,2,3: Lab 

Project Number: ABR-95102: 338-94. Unpublished study prepared by Ciba-Geigy 

Corp. 9 p. 

44083203 Krueger, J.; Smith, K.; Butz, R. (1990) Comparative Aerobic Soil Degradation of 

SAN 582H, Alachlor, and Metolachlor: Lab Project Number: 414105-9: DP300038: 414105. Unpublished study prepared by Sandoz Agro, Ltd. 19 p. 

15656 Dupre, G.D. (1974) Abbreviated Anaerobic Metabolism of 14C-CGA- 24705 in 

Silt Loam Soil under Greenhouse Conditions: Report No. 73019-3. (Unpublished 

study received Sep 26, 1974 under 5G1553; prepared by Bio/dynamics, Inc., 

submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:094222-B) 

41309801 Spare, W. (1989) Soil Metabolism of Metolachlor under Aerobic, 

Aerobic/Anaerobic, and Sterile Conditions: Lab Project Number: 1258. 

Unpublished study prepared by Agrisearch Inc. in association with Ciba-Geigy 

Corp. 130 p. 

41309802 Spare, W. (1989) Soil Metabolism of Metalochlor under Aerobic, 

Aerobic/Anaerobic, and Sterile Conditions: Lab Project Number: 1258. 

Unpublished study prepared by Agrisearch, Inc. 130 p. 

41185701 Spare, W. (1989) Aerobic and Anaerobic Aquatic Metabolism of Meta- lachlor: 

Final Report: Study No. 1259. Unpublished study pre- pared by Agrisearch Inc. 

140 p. 

15657 Dupre, G.D. (1974) Leaching Characteristics of 14C-CGA-24705 and Its 

Degradation Products Following Aging in Sandy Loam Soil un- der Greenhouse 

Conditions: Report No. 73021-6. (Unpublished study received Sep 26, 1974 under 

5G1553; prepared by Bio/ dynamics, Inc., submitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:094222-C) 

15658 Dupre, G.D. (1974) Runoff Characteristics of 14C-CGA-24705 Applied to Sandy 

Loam Soil under Greenhouse Conditions: Report No. 73022-1. (Unpublished 

study received Sep 26, 1974 under 5G1553; prepared by Bio/dynamics, Inc., 

submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:094222-D) 

15659 Houseworth, L.D. (19??) Report on Parent Leaching Studies for CGA- 24705: 

Report No. 1. (Unpublished study received Sep 26, 1974 under 5G1553; prepared 
48 

by Univ. of Missouri, Dept. of Plant Pathology, submitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:094222-E) 

31327 Black, D.K. (1978) Adsorption-Desorption Study Using Antor Herbi- cide. 

(Unpublished study received May 3, 1979 under 43142-1; submitted by Boots 

Hercules Agrochemicals Co., Wilmington, Del.; CDL:098274-G) 

31328 Harvey, R.G.; Jordan, G.L. (1978) Comparative Study of the Biologi- cal and 

Physical Properties of Acetanilide Herbicides in Soil. (Unpublished study received 

May 3, 1979 under 43142-1; prepared by Univ. of Wisconsin, submitted by Boots 

Hercules Agrochemicals Co., Wilmington, Del.; CDL:098274-H) 

31329 Jordan, G.L.; Harvey, R.G. (1978) Environmental Factors and Soil Relationships 

Influencing the Activity of Acetanilide Herbi- cides. Doctoral Thesis, Univ. of 

Wisconsin, Dept. of Agronomy. (pp. 22-58 only; unpublished study received May 

3, 1979 under 43142-1; submitted by Boots Hercules Agrochemicals Co., 

Wilming- ton, Del.; CDL:098274-I) 

32172 Herman, M.M.; Nixon, W.B.; Ball, J.; et al. (1980) ?Soil Dissapa- tion of 

Herbicides|: Report No. ABR-80017. (Unpublished study including AG-A No. 

5409 I-V received Apr 30, 1980 under 100-597; prepared in cooperation with 

Uniroyal Inc., submitted by Ciba- Geigy Corp., Greensboro, N.C.; CDL:242551-

A) 

78291 Burkhard, N. (1978) Adsorption and Desorption of Metolachlor (Dual^(R)I) in 

Various Soil Types: Project Report 45/78. (Un- published study received Jul 23, 

1981 under 100-587; prepared by Ciba-Geigy, Ltd., Switzerland, submitted by 

Ciba-Geigy Corp., Greensboro, N.C.; CDL:245627-D) 

78301 Guth, J.A. (1975) CGA-24705 Leaching Model Study with the Herbicide CGA24705 in Four Standard Soils: Nr. SPR 3/75. (Unpublished study received Jul 23, 

1981 under 100-587; prepared by Ciba- Geigy, Ltd., Switzerland, submitted by 

Ciba-Geigy Corp., Greens- boro, N.C.; CDL:245628-E) 

118040 Burkhard, N.; Guth, J. (1981) Rate of volatilisation of pesticides from soil 

surfaces: Comparison of calculated results with those determined in a laboratory 

model system. Pestic. Sci. 12(1): 37-44. (Also In unpublished submission received 

Nov 5, 1982 under 4581-351; submitted by Agchem Div., Pennwalt Corp., 

Philadelphia, PA; CDL:248818-X) 

153668 Bouchard, D.; Lavy, T.; Marx, D. (1982) Fate of metribuzin, meto- lachlor, and 

fluometuron in soil. Weed Science 30:629-632. 

40494602 Spare, W. (1987) Leaching Characteristics of Parent Metolachlor: Laboratory 

Study No. 1234. Unpubllshed study prepared by Agrisearch, Inc. 77 p. 

40494603 Spare, W. (1987) Leaching Characteristics of Aged Metolachlor: Laboratory 

Study No. 1233. Unpublished study prepared by Agrisearch, Inc. 53 p. 
49 

40494604 Spare, W. (1987) Determination of Adsorption/Desorption Constants of 

Metolachlor: Agrisearch Project No. 1235. Unpublished study prepared by 

Agrisearch, Inc. 79 p. 

40494605 Spare, W. (1988) Determinations of Adsorption/Desorption Constants of CGA51202: Agrisearch Project No. 1266. Unpublished study prepared by Agrisearch, 

Inc. 66 p. 

40629103 Spare, W. (1987) A Supplemental to the Determination of Adsorption Desorption 

Constants of ?carbon 14|-CGA-154281. Unpublished study prepared by CibaGeigy Corp. 41 p. 

43928937 Spare, W.C. ADSORPTION/DESORPTION OF 14c-c~~-771B0Y2 THE BATCH 

EOUILIBRIUM METHOD ON REPRESENTATIVE AGRICULTURAL SOILS. 

Sponsored and Submitted by Ciba-Geigy Protection, Ciba-Geigy Corporation, 

Greensboro, NC under Ciba-Geigy Study No. 71-95 and Agrisearch Project No. 

12218; Study completed on 11 July 1995; Received by EPA 26 January 1996; 

MRID 43928937. 

43928938 Spare, W.C. LEACHING CHARACTERISTICS OF AGED 1 4 CGA 77102 in 

Four SOILTYPES. Sponsored and Submitted by Ciba-Geigy Protection, CibaGeigyCorporation, Greensboro, NC under Study No. 72-95; Performed by 

A grisearch Incorporated, Frederick, MD under Agrisearch Project No. 

18216; Study completed on 22 December 1995; Received by EPA 26 

January 1996; MRID 43928938 

44931722 Spare, W. (1997) Adsorption/Desorption of (carbon-14-CGA-354743) By the 

Batch Equilibrium Method on Representative Agricultural Soils: Lab Project 

Number: 92-97: 12240. Unpublished study prepared by Agrisearch, Inc. 252 p. 

 

40494606 Spare, W. (1987) The Volatilization of Metolachlor from Soil (A Laboratory 

Study): Agrisearch Project No. 1260. Unpublished study prepared by Agrisearch, 

Inc. 60 p. 

15610 Ballantine, L.G.; Herman, M.M. (1978) Dual^(R)I plus Bladex^(R)I Tank Mix 

Soil Dissipation Studies: Report No. ABR-78071. Summa- ry of studies 235360-

C, 235360-D and 235360-G through 235360-J. (Unpublished study received Oct 

20, 1978 under 100-583; submit- ted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:235360-A) 

16303 Sumner, D.D.; Cassidy, J.E. (1975) The Degradation of CGA-24705 in a Field 

Soil: Report No. GAAC-75022. (Unpublished study re- ceived on unknown date 

under 5F1606; submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:094385-

N) 

23515 Ballantine, L.G.; Herman, M.M.; Coan, R.M.; et al. (1979) Bi- cep^(R)I plus 

Roundup^(R)I or Paraquat and Dual^(R)I/Prin- cep^(R)I plus Roundup or 

Paraquat Tank Mix Soil Dissipation Studies: Report No. ABR-79101. 
50 

(Unpublished study received Dec 10, 1979 under 100-583; prepared in 

cooperation with Chevron Chemical Co. and others, submitted by Ciba-Geigy 

Corp., Greens- boro, N.C.; CDL:241649-A) 

27018 Ballantine, L.G.; Herman, M.M. (1979) Bicep^(R)I plus Roundup^(R)I or 

Paraquat and Dual^(R)I/Princep^(R)I plus Roundup or Paraquat Tank Mix Soil 

Dissipation Studies: Report No. ABR-79101. Sum- mary of studies 241649-B 

through 241649-Q. (Unpublished study received Dec 10, 1979 under 100-583; 

submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:241649-A) 

64174 Herman, M.M.; Nixon, W.B. (1980) Dual^(R)I plus Premerge^(R)I Tank Mix Soil 

Dissipation Studies: Report No. ABR-80021. (Unpub- lished study received Mar 

31, 1981 under 100-597; submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL:099991-A) 

 Metolachlor Plus Propazine Tank Mix Soil Dissinatioc ( r e p o r t 

#RBR-78037) Vol. 8 of 8, EPA P i l e No. 100-ANU. 

L. G. Ballantine and M. M. Herman, April 27, 1978. 

64178 Herman, M.M.; Nixon, W.B. (1980) Dual^(R)I plus Eptam^(R)I Tank Mix Soil 

Dissipation Studies: Report No. ABR-80022. (Unpublished study received Mar 

31, 1981 under 100-597; submitted by Ciba- Geigy Corp., Greensboro, N.C.; 

CDL:099990-A) 

134319 Herman, M.; Newby, L. (1978) Dual plus Dyanap Tank Mix: Soil Dissi- pation 

Studies: ?Summary|: Report No. ABR-78069. (Unpublished study received Oct 

11, 1979 under 100-583; submitted by Ciba- Geigy Corp., Greensboro, NC; 

CDL:241132-A) 

41309803 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa--Site A: Lab 

Project Number: 1265/A. Unpublished study prepared by Agrisearch Inc. 324 p. 

41309804 Merricks, D. (1989) Metolachlor Field Dissipation Study in California--Site C: 

Lab Project Number: 1264/C. Unpublished study prepared by Agrisearch, Inc. 334 

p. 

41309805 Merricks, D. (1989) Metolachlor Field Dissipation Study in California--Site C: 

Lab Project Number: 1265/C. Unpublished study prepared by Agrisearch, Inc. 334 

p. 

41335701 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa--Site B: Final 

Report: Lab Project Nos. 1264-B; 1264. Unpublished study prepared by 

Agrisearch Inc. 300 p. 

41335702 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa--Site B: Final 

Report: Lab Project Number 1265-B; 1265. Unpublished study prepared by 

Agrisearch Inc. 298 p. 

41484201 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa-- Site A: 

Amendment to Final Report: Unpublished study prepared by Ciba-Geigy Corp. 6 

p. 
51 

41484202 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa-- Site A: 

Amendment to Final Report. Unpublished study prepared by Ciba-Geigy Corp. 6 

p. 

41484203 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa-- Site B: 

Amendment To Final Report. Unpublished study prepared by Ciba-Geigy Corp. 7 

p. 

41484204 Merricks, D. (1989) Metolachlor Field Dissipation Study in Iowa-- Site B. 

Unpublished study prepared by Ciba-Geigy Corp. 7 p. 

41484205 Merricks, D. (1989) Metolachlor Field Dissipation Study in Cali- fornia--Site C: 

Amendment to Final Report. Unpublished study prepared by Ciba-Geigy Corp. 6 

p. 

41484206 Merricks, D. (1989) Metolachlor Field Dissipaation Study In Califor nia--Site C: 

Amendment to Final Report. Unpublished study pre- pared by Ciba-Geigy Corp. 6 

p. 

43267304 Balu, K.; Smith, J.; Nelson, D. (1994) Response to EPA Review of the Terrestrial 

Field Dissipation Studies on Metolachlor: Lab Project Number: ABR-94023: 

130000. Unpublished study prepared by Ciba-Geigy Corp. 49 p. 

40114402 Honeycutt, R. (1986) Terrestrial Dissipation of Metolachlor (Dual): Laboratory 

Study No. EIR-86031. Unpublished study prepared by Ciba-Geigy Corp. 754 p. 

67894 Ellgehausen, H.; Guth, J.A.; Esser, H.O. (1978) Factors Determining the 

Bioaccumulation Potential of Pesticides in the Individual Compartments of 

Aquatic Food Chains. (Unpublished study re- ceived Jan 28, 1981 under 100-618; 

prepared by Ciba-Geigy, Ltd., Switzerland, submitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:244270-B) 

126717 Dickson, G. (1983) Environmental Impact of Technical CGA-112913 under 

Specified EUP Conditions: Report No. EIR-83006. (Unpub- lished study received 

Apr 4, 1983 under 100-EX-79; submitted by Ciba-Geigy Corp., Greensboro, NC; 

CDL:249870-A; 249871) 

40494607 Surprenant, D. (1988) Bioconcentration and Elimination of ?Carbon 14|-Residues 

by Bluegill (Lepomis macrochirus) Exposed to Metolachlor: Laboratory Study 

No. 87-9-2505. Unpublished study prepared by Springborn Life Sciences, Inc. 64 

p. 

41154201 Fackler, P. (1989) Bioconcentration and Elimination of ?Carbon 14| Residues by 

Bluegill (Lepomis macrochirus) Exposed to Metola- chlor: Laboratory Report No. 

87-9-2505. Unpublished study pre- pared by Springborn Life Sciences, Inc. 188 p. 

41523601 Fackler, P. (1989) Metolachlor: Amendment to the Final Report: Bioconcentration and Elimination of ?carbon 14| Residues by Blue- gill (Lepomis 

macro-chirus) Exposed to Metolachlor: Lab Project No: ABR-89019. 

Unpublished study prepared by Springborn Labora- tories, Inc. 105 p. 
52 

16298 Barrows, M.E. (1974) Research report submitted to Ciba-Geigy Corporation: 

Exposure of fish to 14C-CGA-24705: Accumulation, distribution, and elimination 

of 14C-residues. Unpublished study received Mar. 27, 1975 under 5F1606; 

prepared by Bionomics, EG&G Environmental Consultants, submitted by CibaGeigy Corporation, Greensboro, NC; CDL: 094376-R. 

44002501 Fuhrman, J. (1996) Analytical Method Development and First Year Performance: 

GC/MS Analytical Methodology to Support the Acetochlor Registration 

Partnership Surface Water and Ground Water Monitoring Studies: Progress 

Report: Lab Project Number: MSL-14562: M001/1: ACET-95-GW-02. 

Unpublished study prepared by Ceregen, a Unit of Monsanto Co. 344 p. 

44226601 Alexander, S.; Klein, T.; Stone, C.; et al. (1996) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor (Dual) at a Worst-Case 

Vulnerable Site in Southeastern United States: Progress Report #6: Lab Project 

Number: 276-93: 93101. Unpublished study prepared by Stone Environmental 

Inc.; Research Options, Inc.; and Ciba Crop Protection. 33 p. (Relates to I004412). 

44262101 Alexander, S.; Stone, C.; Gold, B. (1997) A Small Scale Prospective Groundwater 

Monitoring Study for Metolachlor (Dual) at a Worst-Case Vulnerable Site in 

Southeastern United States: Progress Report #7: Lab Project Number: 276-93: 

93101. Unpublished study prepared by Stone Environmental, Inc., Research 

Options, Inc., Novartis Crop Protection, Inc. 41 p. 

44333901 Alexander, S.; Stone, C.; Gold, B. (1997) A Small Scale Prospective Groundwater 

Monitoring Study for Metolachlor (Dual) at a Worst-Case Vulnerable Site in 

Southeastern United States: Progress Report #8: Lab Project Number: 276-93: 

93101. Unpublished study prepared by Research Options, Inc.; Stone 

Environmental, Inc.; and Novartis Crop Protection, Inc. 40 p. 

44333902 Keen, K. (1997) A Small-Scale Prospective Groundwater Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #4: Lab Project Number: 656-95: SG-954850. Unpublished study 

prepared by Summit Envirosolutions, Inc. and Novartis Crop Protection, Inc. 30 p. 

44424501 Keen, K. (1997) A Small-Scale Prospective Ground Water Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #5: Lab Project Number: 656-95: SG-954850. Unpublished study 

prepared by Summit Envirosolutions, Inc. 53 p. 

44424502 Alexander, S.; Stone, C.; Gold, B. (1997) A Small-Scale Prospective Ground 

Water Monitoring Study for Metolachlor (Dual) at a Worst-Case Vulnerable Site 

in the Southeastern United States: Progress Report #9: Lab Project Number: 276-

93: 93101. Unpublished study prepared by Stone Environmental, Inc. and 

Research Options, Inc. 40 p. 
53 

44483701 Keen, K. (1998) A Small-Scale Prospective Ground Water Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #6: Lab Project Number: 656-95: SG-954850. Unpublished study 

prepared by Summit Envirosolutions, Inc. and Novartis Crop Protection, Inc. 49 p. 

44483702 Alexander, S.; Stone, C.; Gold, B. (1998) A Small Scale Prospective Groundwater 

Monitoring Study for Metolachlor (Dual) at a Worst-Case Vulnerable Site in 

Southeastern United States: Progress Report #10: Lab Project Number: 276-93: 

93101. Unpublished study prepared by Stone Environmental, Inc., Research 

Options, Inc. and Novartis Crop Protection, Inc. 34 p. 

44545401 Alexander, S.; Stone, C.; Gold, B. (1998) A Small Scale Prospective Groundwater 

Monitoring Study for Metolachlor (Dual) at a Worst-Case Vulnerable Site in 

Southeastern United States: Progress Report #11: Lab Project Number: 276-93: 

93101. Unpublished study prepared by Novartis Crop Protection, Inc., Stone 

Environmental, Inc., and Research Options, Inc. 37 p. 

44545402 Keen, K. (1998) A Small-Scale Prospective Ground Water Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #7: Lab Project Number: 656-95: SG-954850. Unpublished study 

prepared by Novartis Crop Protection, Inc., and Summit Envirosolutions, Inc. 48 

p. 

44619901 Alexander, S.; Stone, C.; Gold, B. (1998) A Small Scale Prospective Groundwater 

Monitoring Study for Metolachlor (Dual) at a Worst-Case Vulnerable Site in 

Southeastern United States: Lab Project Number: 276-93: 93101. Unpublished 

study prepared by Stone Environmental, Inc., Novartis Crop Protection, Inc. and 

Research Options, Inc. 29 p. 

44619902 Keen, K. (1998) A Small Scale Prospective Groundwater Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #8: Lab Project Number: 656-95: SG-954850. Unpublished study 

prepared by Summit Envirosolutions, Inc. and Novartis Crop Protection, Inc. 54 p. 

44687801 Alexander, S.; Stone, C.; Gold, B. (1998) A Small Scale Prospective Groundwater 

Monitoring Study for Metolachlor (Dual) at a Worst Case Vulnerable Site in 

Southeastern United States: Progress Report #13: Lab Project Number: 276-93: 

93101. Unpublished study prepared by Stone Environmental, Inc. and Research 

Options, Inc. 30 p. 

44687802 Keen, K. (1998) A Small Scale Prospective Groundwater Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #9: Lab Project Number: 656-95: SG-954850. Unpublished study 

prepared by Summit Envirosolutions, Inc. and Novartis Crop Protection, Inc. 54 p. 

44754001 Keen, K. (1999) A Small-Scale Prospective Ground Water Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Progress Report #10: Lab Project Number: 65-95: SG-954850. Unpublished study 

prepared by Summit Envirosolutions, Inc. and Novartis Crop Protection, Inc. 46 p. 
54 

44837101 Keen, K. (1999) A Small-Scale Prospective Ground Water Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Interim Report: Progress Report No. 11: Lab Project Number: 656-95: SG954850. Unpublished study prepared by Summit Envirosolutions, Inc. 45 p. 

44898101 Keen, K. (1999) A Small-Scale Prospective Ground Water Monitoring Study for 

CGA-77102 at a Worst-Case Vulnerable Site in the Midwestern United States: 

Lab Project Number: SG-954850: 656-95. Unpublished study prepared by Summit 

Envirosolutions, Inc., and Novartis Crop Protection, Inc. 46 p. 

45316601 Hackett, A. (2000) ARP SWM Program Analytical Results of the ARP Program 

Year 2000 through August for Parent Herbicides and Year 2000 Samples 

Analyzed to Date for Degradates: Lab Project Number: SWM1100. Unpublished 

study prepared by Monsanto Company. 81 p. 

45840501 Jenkins, D.; Kelley, J.; Peterson, R. (2002) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Lab Project Number: 02-110. 

Unpublished study prepared by Research Options, Inc., Kelley Consulting 

Geology, Agvise Laboratories and Harbor QA Services, Inc. 17 p. 

45903901 Jenkins, D.; Kelley, J.; Peterson, R. (2003) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Lab Project Number: 02-110. 

Unpublished study prepared by Research Options, Inc. and Enviro-Test 

Laboratories, Inc. 20 p. 

45940701 Jenkins, D.; Kelley, J.; Peterson, R. (2003) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Lab Project Number: 02-110: 

MN-18-WW-1. Unpublished study prepared by Research Options, Inc., EnviroTest Laboratories, Inc. and Agvise Laboratories. 93 p. 

45943601 Jenkins, D.; Kelley, J.; Peterson, R. (2003) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Lab Project Number: 02-110. 

Unpublished study prepared by Research Options, Inc., Agvise Laboratories, and 

Enviro-Test Laboratories, Inc. 93 p. 

46029801 Vargo, J. (1998) Determination of Metolachor (CGA-24705) And CGA-77102, 

and Their Degradates CGA-51202, CGA-354743, CGA-380168, CGA-37735, 

CGA-67125, and CGA-41638 in Water by High Performance Liquid 

Chromatography with Mass Spectrometric Detection Including Validation Data. 

Project Number: AG/682, 68/98. Unpublished study prepared by Syngenta Crop 

Protection, Inc. 150 p. 

46185701 Jenkins, D.; Kelley, J.; Peterson, R. (2004) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor. Project Number: 02/110, 

MN/18/WW/1, DY/55/TH1. Unpublished study prepared by Research Options, 

Inc., Kelly Consulting Geology, and Harbor QA Services, Inc. 214 p. 
55 

46330301 Jenkins, D.; Kelley, J.; Peterson, R. (2004) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Progress Report 2 - Sample 

Collection and Site Monitoring Through 186 Days After Treatment. Project 

Number: 02/110. Unpublished study prepared by Research Options, Inc., EnviroTest Laboratories (ETL) and Agvise Inc. 190 p. 

46486201 Jenkins, D.; Kelley, J.; Peterson, R. (2005) A Small Scale Groundwater 

Monitoring Study for Metolachlor: Progress Report 3 - Sample Collection and 

Analysis Through 269 Days After Treatment. Project Number: 02/110. 

Unpublished study prepared by Research Options, Inc., Enviro-Test Laboratories, 

and Agvise Laboratories. 197 p. 

46691001 Jenkins, D.; Kelley, J.; Peterson, R. (2005) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor. Project Number: 02/110. 

Unpublished study prepared by Research Options, Inc., Kelly Consulting Geology 

and Harbor QA Services, Inc. 257 p. 

46734201 Jenkins, D.; Kelley, J.; Peterson, R. (2006) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor. Project Number: 02/110. 

Unpublished study prepared by Research Options, Inc., Kelly Consulting Geology 

and Harbor QA Services, Inc. 256 p. 

46837601 Jenkins, D.; Kelley, J.; Peterson, R. (2006) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor Progress Report 6 - Sample 

Collection and Analysis Through 939 Days After Treatment. Project Number: 

02/110. Unpublished study prepared by Research Options, Inc., Enviro-Test 

Laboratories (ETL) and Harbor QA Services, Inc. 276 p. 

46837602 Jenkins, D.; Kelley, J.; Peterson, R. (2006) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Termination Request Report. 

Project Number: 02/110. Unpublished study prepared by Research Options, Inc., 

Enviro-Test Laboratories (ETL) and Agvise Laboratories. 22 p. 

44002501 Fuhrman, J. (1996) Analytical Method Development and First Year Performance: 

GC/MS Analytical Methodology to Support the Acetochlor Registration 

Partnership Surface Water and Ground Water Monitoring Studies: Progress 

Report: Lab Project Number: MSL-14562: M001/1: ACET-95-GW-02. 

Unpublished study prepared by Ceregen, a Unit of Monsanto Co. 344 p. 

44136501 Cheung, M. (1996) Metolachlor Residues in Ground Water from Ciba/State 

Ground Water Monitoring Studies in the United States of America: Interim Report 

No. 1: Lab Project Number: 91-01: ABR-96041: 101921. Unpublished study 

prepared by Ciba-Geigy Corp. 276 p. 

45058801 Cheung, M. (2000) FIFRA Section 6(a)(2) Annual Ground Water Report for the 

Year 1999. Unpublished study prepared by Novartis Crop Protection, Inc. 23 p. 

45058802 Cheung, M. (2000) FIFRA Section 6(a)(2) Annual Surface Water Report for the 

Year 1999. Unpublished study prepared by Novartis Crop Protection, Inc. 15 p. 
56 

45449601 Guzman, N. (2001) State Ground Water Monitoring Program for Acetochlor and 

Other Corn Herbicides--Part 7: 2000 Progress Report: Lab Project Number: 852-

562: ACET-95-GW-02: 3276.101. Unpublished study prepared by LFR LevineFricke, Monsanto, and Dow AgroSciences LLC. 15 p. 

45629801 Yokley, R. (2002) FIFRA Section 6(a)(2) Annual Ground Water Report for 2001. 

Unpublished study prepared by HAES Resources Department, Syngenta Crop 

Protection, Inc. 33 p. 

45870401 Yokley, R. (2003) FIFRA Section 6(a)2 Annual Ground Water Report for 2002: 

Final Report: Lab Project Number: 2240-02. Unpublished study prepared by 

Syngenta Crop Protection, Inc. 34 p. 

46839502 ECM Method Chemistry repot 2006 Rolando Pet-ez, Jerry Allen, Sung-Ben 

Huang,Thomas Mayer, Steven Perez, Robert Yokley, Novem'jer 1 1, 2005, 

"Analytical Method 

TO1 0097-04 for the Determinatiol? ofAtrazine, Si~nazi~!Ge-,3 0033, G-28279, 

G-28273,Ametryn, Prometryn, GS-11354, GS-11355, GS-26831 and Metolachlor 

in Water Using 

Direct lrzjection LC-ESL:iVS/MS lncllrding Validation Iata. " 

47017401 Jenkins, D.; Kelley, J.; Peterson, R. (2006) A Small Scale Prospective 

Groundwater Monitoring Study for Metolachlor: Final Report. Project Number: 

02/110, MW-U. Unpublished study prepared by Research Options Inc, ALS 

Laboratory Group and Environmental and Agvise Inc. 1490 p. 

45527501 Tierney, D.P., et al. (2001) Exposure Analysis of Metolachlor in Community 

Water System in 27 States, 1993-2000, volume 1-5. Syngenta Crop Protection 

Report No. 2454-01. Unpublished study performed and submitted by Syngenta 

Crop Protection, Inc., Greensboro, NC and En fate, LLC, Plymouth, MN. 

45533102 Chen, Wenlin and T.L. Estes (2001) PRZM3.12 Comparative Modeling of SMetolachlor and Metolachlor Based on Calibration Using Prospective 

Groundwater Studies in Georgia and Minnesota. Syngenta Crop Protection Report 

No. 2501-01. Unpublished study performed and submitted by Syngenta Crop 

Protection, Inc., Greensboro, NC and Stone Environmental Inc., Montpelier, VT 

43766502 Hewitt, A. (1995) Spray Drift Task Force: Atomization Droplet Size Spectra for 

Selective Active Ingredients: Lab Project Number: A92/004. Unpublished study 

prepared by SpraySearch- Daratech Pty. Ltd. and Spray Drift Task Force. 175 p. 

Environmental Fate Studies (S-Metolachlor) 

43928935 Merritt, A. (1995) Photodegradation of (carbon 14)-Metolachlor and (carbon 14)-CGA77102 on Soil Under Artificial Sunlight: Lab Project Number: ABR-95128: 53-95. 

Unpublished study prepared by Ciba Crop Protection. 151 p. 4 p. 
57 

43928936 Clark, A. (1995) Comparative Aerobic Soil Metabolism of Phenyl-(carbon 14)-CGA77102 and Phenyl-(carbon 14)-Metolachlor: Lab Project Number: ABR-95102: 338-

94: 12217. Unpublished study prepared by Ciba Crop Protection and Agrisearch, Inc. 

314 p. 

44043401 Clark, A. (1995) Comparative Aerobic Soil Metabolism of Phenyl-(carbon 14)-CGA77102 and Phenyl-(carbon 14)-Metolachlor: Report Amendments 1,2,3: Lab Project 

Number: ABR-95102: 338-94. Unpublished study prepared by Ciba-Geigy Corp. 9 p. 

45499606 Moore, P. (2000) Soil Metabolism of (Carbon 14)-Phenyl-CGA-77102 Under Aerobic 

and Non-Irradiated Incubation Conditions Following Surface and Homogeneous 

Dosing: Final Report: Lab Project Number: 342-97. Unpublished study prepared by 

Novartis Crop Protection, Inc. 188 p. 

43928937 Spare, W. (1995) Adsorption/Desorption of (carbon 14)-CGA-77102 by the Batch 

Equilibrium Method on Representative Agricultural Soils: Lab Project Number: 12218. 

Unpublished study prepared by Agrisearch, Inc. 179 p. 

43928938 Spare, W. (1995) Leaching Characteristics of Aged (carbon 14)-CGA-77102 in Four 

Soil Types: Lab Project Number: 12216. Unpublished study prepared by Agrisearch, 

Inc. 539 p. 

44931722 Spare, W. (1997) Adsorption/Desorption of (carbon-14-CGA-354743) By the Batch 

Equilibrium Method on Representative Agricultural Soils: Lab Project Number: 92-97: 

12240. Unpublished study prepared by Agrisearch, Inc. 252 p. 

45608301 Ellgehausen, H. (1997) Adsorption/Desorption of CGA-77102 in Various Soils: Final 

Report: Lab Project Number: 97EH01: 851-97. Unpublished study prepared by 

Novartis Crop Protection AG. 70 p. 

45848001 Merritt, A. (2002) Dissipation of CGA-77102 in Soil Under Field Conditions with and 

without Turf (Bare Soil) in Georgia: Final Report: Lab Project Number: 51-99: 51-99 

PART A: PM9901. Unpublished study prepared by Syngenta Crop Protection, Inc. 464 

p. 

46829512 Vargo, J.; Rezaaiyan, R. (1999) Analytical Method for the Determination of CGA77102 and Degradates CGA-51202, CGA-354743, and CGA-37735 in Soil and Thatch, 

and CGA-77102 in Grass by High Performance Liquid Chromatography With Mass 

Spectrometric Detection. Project Number: 127/99. Unpublished study prepared by 

Syngenta Crop Protection, Inc. 76 p. 

44226602 Keen, K. (1997) A Small Scale Prospective Ground Water Monitoring Study for CGA77102 at a Worst-Case Vulnerable Site in the Midwestern United States: Progress 

Report #2: Lab Project Number: 656-95: SG-954850. Unpublished study prepared by 

Summit Envirosolutions, Inc. and Ciba Crop Protection. 43 p. 

44262102 Keen, K. (1997) A Small Scale Prospective Ground Water Monitoring Study for CGA77102 at a Worst-Case Vulnerable Site in the Midwestern United States: Progress 

Report #3: Lab Project Number: SG-954850: 656-95. Unpublished study prepared by 

Summit Envirosolutions, Inc. and Novartis Crop Protection, Inc. 40 p. 
58 

45533101 Francis, P.; Johnson, B. (2001) A Small-Scale Prospective Ground Water Monitoring 

Study for Herbicide S-Metolachlor (CGA-77102) at a Worst-Case Vulnerable Site in 

the Midwestern United States: Final Report: Lab Project Number: 656-95: SG-954850. 

Unpublished study prepared by Summit Envirosolutions, Inc. 570 p. 

45533102 Chen, W.; Estes, T. (2001) PRZM3.12 Comparative Modeling of S-Metolachor and 

Metolachlor Based on Calibration Using Prospective Groundwater Studies in Georgia 

and Minnesota: Final Report: Lab Project Number: 2501-01. Unpublished study 

prepared by Stone Environmental Inc. 82 p. 

46029801 Vargo, J. (1998) Determination of Metolachor (CGA-24705) And CGA-77102, and 

Their Degradates CGA-51202, CGA-354743, CGA-380168, CGA-37735, CGA67125, and CGA-41638 in Water by High Performance Liquid Chromatography with 

Mass Spectrometric Detection Including Validation Data. Project Number: AG/682, 

68/98. Unpublished study prepared by Syngenta Crop Protection, Inc. 150 p. 

44527503 Chen, Wenlin, 200 1. Concentration Trend of Metolachlor and S-Metolachlor 

Resulting from the Reduced Use Rate of S-Metolachlor in Ohio Lake Erie Tributary 

Drainage Basins. Syngenta Crop Praection Report No. 1663-0 1. Unpublished study 

performed and submitted by Syngenta Crop Protection, Inc., Greensboro, NC. 

 Registrant Summary of adsorption Studies 1978-1987 with Metolachlor 

 

 

44303502 Murphy, T.; Clark, A.; Merritt, A. (1997) Response to EPA Review of CGA77102/Metolachlor Environmental Fate Studies: Lab Project Number: ABR-97049. 

Unpublished study prepared by Novartis Crop Protection, Inc. 45 p. 

45499601 Needham, J.; Brady, J. (1999) Analytical Method for the Semi-Quantitative 

Determination of CGA-77102 in Water by Enzyme Immunoassay Including Validation 

Data: Lab Project Number: 1004-98. Unpublished study prepared by Novartis Crop 

Protection, Inc. 40 p. 

45499602 Meyer, L. (2001) An Assessment of the Toxicological Profiles of Two Major 

Environmental Degradates of S-Metolachlor (Ethane Sulfonic Acid and Oxanilic Acid) 

and a Rationale for Establishing Separating Drinking Water Standards: Final Report: 

Lab Project Number: 2121-01. Unpublished study prepared by Syngenta Crop 

Protection, Inc. 56 p. 

45527502 Tierney, D.; Marut, K.; Dando, C. et al. (2001) Occurrence of Metolachlor (1994-1995) 

Compared to S-Metolachlor (1999-2000) in Drinking Water From Community Water 

Systems in 27 Major Use States: Lab Project Number: 2455-01: 00025. Unpublished 

study prepared by Syngenta Crop Protection, Inc. 23 p. 

45527503 Chen, W. (2001) Concentration Trend of Metolachlor and S-Metolachlor Resulting 

from the Reduced Use Rate of S-Metolachor in Ohio Lake Erie Tributary Drainage 
59 

Basins: Final Report: Lab Project Number: 1663-00. Unpublished study prepared by 

Syngenta Crop Protection, Inc. 96 p. 

45672301 Hipps, A. (2002) Physical and Chemical Properties of S-Metolachlor (CGA-77102) 

Technical: Lab Project Number: PC-02-035. Unpublished study prepared by Syngenta 

Crop Protection, Inc. 23 p. {OPPTS 830.7050} 

46224201 Trask, J.; Harbourt, C.; Johnson, L.; et. al. (2003) 2001 S-Metolachlor Monitoring Data 

for Community Water Systems in 29 States: Final Report. Project Number: 

WEI/242/59/001, T001594/03, 242/59/001. Unpublished study prepared by 

Waterborne Environmental, Inc. (WEI). 1775 p. 

45527501 Tierney, D.; Marut, K.; Dando, C. et al. (2001) Exposure Analysis of Metolachlor in 

Community Water Systems in 27 Use States, 1993-2000: Lab Project Number: 2454-

01: 00024. Unpublished study prepared by Syngenta Crop Protection, Inc. 1771 p. 

46224202 Trask, J.; Harbourt, C.; Johnson, L.; et. al. (2003) 2002 S-Metolachlor Monitoring Data 

for Community Water Systems in 43 States: Final Report. Project Number: 

WEI/242/59/002, 242/59/002, T001596/03. Unpublished study prepared by 

Waterborne Environmental, Inc. (WEI). 1785 p. 

46484201 Merritt, A. (2005) FIFRA Section 6(a)(2) Annual Report for S-Metolachlor Monitoring 

Data from the 2004 Atrazine Monitoring Program (AMP) for Selected Community 

Water Systems (CWS) on Surface Water Sources: S-Metolachlor: Final Report. Project 

Number: T003232/05. Unpublished study prepared by Syngenta Crop Protection, Inc. 

64 p. 

46818801 Indergand, P.; Nicollier, G. (2006) Production and Analysis of Leachates in Outdoor 

Lysimeters Treated with [Phenyl-U-(Carbon 14)]-CGA 77102: Final Report. Project 

Number: 02GN05, T003712/02. Unpublished study prepared by Syngenta Crop 

Protection, AG. 232 p. 

47067701 Perez, R.; Merritt, A.; Perez, S. (2007) S-Metolachlor: FIFRA Section 6(a)(2) Annual 

Report for S-Metolachlor Monitoring Data from the 2006 Atrazine Monitoring 

Program, 2006 Simazine Monitoring Program and 2006 Simazine Confirmatory 

Monitoring Program for Selected Community Water Systems Relying on Surface 

Water Sources: Final Report. Project Number: 2K6/901/0766/06/02, T000766/06. 

Unpublished study prepared by ADPEN Laboratories, Inc. 18 p. 

47358801 Perez, R.; Perez, S.; Merritt, A. (2008) S-Metolachlor FIFRA Section 6(a)(2) Annual 

Report for S-Metolachlor Monitoring Data from the 2007 Atrazine Monitoring 

Program, 2007 Simazine Monitoring Program, 2007 Simazine Confirmatory 

Monitoring Program and 2007 Stewardship Voluntary Monitoring Program for 

Selected Community Water Systems Relying on Surface Water Sources: Final Report. 

Project Number: 2K7/901/766/06/01. Unpublished study prepared by ADPEN 

Laboratories, Inc. 18 p. 
60 

46029802 Yodley, R.A. and M.W. Cheung (2002) Syngenta/Community Water System Surface 

Water Monitoring Study for Atrazine and its Major Degradation Products in Seven 

States in the United States (Supplemental to EPA MRID 45058703 and MRID 

45145601); Supplementary Report 2 – Data for Metolachlor and its Major Metabolites 

(ESA and OA). Syngenta Crop Protection Report 419-97. Unpublished study 

performed and submitted by Syngenta Crop Protection, Inc., Greensboro, NC. 

 

46029801 Vargo, J. (1998) Determination of Metolachor (CGA-24705) And CGA-77102, and 

Their Degradates CGA-51202, CGA-354743, CGA-380168, CGA-37735, CGA67125, and CGA-41638 in Water by High Performance Liquid Chromatography with 

Mass Spectrometric Detection Including Validation Data. Project Number: AG/682, 

68/98. Unpublished study prepared by Syngenta Crop Protection, Inc. 150 p. 

Cited Ecological Effects Studies Ecological Effects Studies 

00015523 Bathe, R. (1973) Acute Oral LD-50 of Technical CGA-24705 in the Rat: Project 

No. Siss 2979. Received September 26, 1974 under 5G1553. (Unpublished report 

prepared by CIBA-GEIGY Ltd., Basle, Switzerland; CDL: 112840-A 

00015534 Sachsse, K.; Ullmann, L. (1974) Acute Toxicity to Rainbow Trout, Crucian Corp, 

Channel Catfish, Bluegill and Guppy of Technical CGA-24705: Project No. Siss 

3516. (Unpublished study received Mar 1, 1974 under 5G1553; prepared by CibaGeigy, Ltd., submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:094220-M) 

00015546 Vilkas, A.G. (1976) Acute Toxicity of CGA-24705 Technical to the Water Flea, 

Daphnia magna Straus. (Unpublished study received Nov 24, 1976 under 100-

587; prepared by Union Carbide Corp., submitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:226955-E) 

00015547 Fink, R. (1976) Final Report: Acute Oral LD50--Mallard Duck: Project No. 108-

117. (Unpublished study received Nov 24, 1976 under 100-587; prepared by 

Truslow Farms, Inc. in cooperation with Maryland, Dept. of Agriculture, Division 

of Inspection and Regulation, submitted by Ciba-Geigy Corp., Greensboro, N.C.; 

CDL: 226955-F) 

00016425 Fink, R. (1974) Final Report: Eight-Day Dietary LC50--Mallard Ducks: Project 

No. 108-111. (Unpublished study received on un- known date under 5G1553; 

prepared by Truslow Farms, Inc. in cooperation with Maryland, Dept. of 

Agriculture, Div. of Inspection and Regulation, submitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:094220-O) 

00016426 Fink, R. (1974) Final Report: Eight-Day Dietary LC50--Bobwhite Quail: Project 

No. 108-110. (Unpublished study received on unknown date under 5G1553; 

prepared by Truslow Farms, Inc. in cooperation with Maryland, Dept. of 
61 

Agriculture, Div. of Inspection and Regulation, submitted by Ciba-Geigy Corp., 

Greensboro, N.C.; CDL:094220-P) 

00018722 Buccafusco, R.J.; Stiefel, C.; Sullivan, D.M.; et al. (1978) Acute Toxicity of 

CGA-24705 to Rainbow Trout (Salmo gairdneri): Report #BW-78-6-186. 

(Unpublished study received Jul 13, 1978 under 100-597; prepared by EG&G, 

Bionomics, submitted by Ciba- Geigy Corp., Greensboro, N.C.; CDL:234396-B) 

00018723 Buccafusco, R.J.; Stiefel, C.; Sullivan, D.M. (1978) Acute Toxicity of CGA24705 to Bluegill (Lepomis macrochirus): Report #BW- 78-6-181. (Unpublished 

study received Jul 13, 1978 under 100- 597; prepared by EG&G, Bionomics, 

submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:234396-C) 

00062465 Fink, R.; Beavers, J.B.; Brown, R.; et al. (1981) Final Report: Acute Oral LD50--

Mallard Duck: Project No. 108-200. (Unpublished study received Mar 31, 1981 

under 100-587; prepared by Wildlife International, Ltd. and Washington College, 

submitted by Ciba-Geigy Corp., Greensboro, N.C.; CDL:244691-B) 

00162292 Beavers, J. (1978) One Generation Reproduction Study - Mallard Duck: 

Metolachlor Technical (CGA - 24705): Final Report. Un- published study 

prepared by Wildlife International Ltd. 29 p. 

43044602 Ward, S. (1980) Metolachlor: Effects of metolachlor (Dual) on Survival, growth, 

and Development of Sheepshead Minnow (Cyprinodon variegatus): Lab Project 

Number: BP-80-5-80: L33. Unpublished study prepared by EG&G Bionomics, 

Marine Research Lab. 32 p. 

43487101 Machado, M. (1994) Metolachlor Technical--Acute Toxicity to Sheepshead 

Minnow (Cyprinodon variegatus) Under Flow-through Conditions: (Final 

Report): Lab Project Number: 94-7-5378: 1781.0394.6422.505. Unpublished 

study prepared by Springborn Labs, Inc. 70 p. 

43487102 Dionne, E. (1994) Metolachlor Technical--Acute Toxicity to Eastern Oyster 

(Crassostrea virginica) Under Flow-through Conditions: (Final Report): Lab 

Project Number: 94-7-5365: 1781.0394.6423.504. Unpublished study prepared by 

Springborn Labs, Inc. 76 p. 

43487103 Machado, M. (1994) Metolachlor Technical--Acute Toxicity to Mysid Shrimp 

(Mysidopsis bahia) Under Flow-through Conditions: (Final Report): Lab Project 

Number: 94-7-5402: 1781.0394.6421.515. Unpublished study prepared by 

Springborn Labs, Inc. 75 p. 

43487104 Hoberg, J. (1994) Metolachlor Technical--5-Day Toxicity to the Freshwater Green 

Alga, Anabaena flos-aquae: (Final Report): Lab Project Number: 94-7-5383: 

1781.0394.6427.420. Unpublished study prepared by Springborn Labs, Inc. 65 p. 

43487105 Hoberg, J. (1994) Metolachlor Technical--Toxicity to Duckweed (Lemna gibba): 

(Final Report): Lab Project Number: 94-8-5404: 1781.0394.6428.410. 

Unpublished study prepared by Springborn Labs, Inc. 71 p. 
62 

43487106 Hoberg, J. (1994) Metolachlor Technical--Toxicity to the Marine Diatom, 

Skeletonema costatum: (Final Report): Lab Project Number: 94-7-5382: 

1781.0394.6426.450. Unpublished study prepared by Springborn Labs, Inc. 67 p. 

43487107 Chetram, R. (1994) Tier 2 Seedling Emergence Nontarget Phytotoxicity Study 

Using Metolachlor: Lab Project Number: 94349. Unpublished study prepared by 

Pan-Agricultural Labs, Inc. 180 p. 

43487108 Chetram, R. (1994) Tier 2 Vegetative Vigor Nontarget Phytotoxicity Study Using 

Metolachlor: Lab Project Number: 94350. Unpublished study prepared by PanAgricultural Labs, Inc. 175 p. 

43541301 Hoberg, J. (1995) Metolachlor Technical--5-Day Toxicity to the Freshwater Green 

Alga, Selenastrum capricornutum, Using Acetone as a Carrier Solvent: (Final 

Report): Lab Project Number: 94-12-5621: 1781.1294.6467.430. Unpublished 

study prepared by Springborn Labs, Inc. 68 p. 

43541302 Hoberg, J. (1995) Metolachlor Technical--5-Day Toxicity to the Freshwater 

Diatom, Navicula pelliculosa, Using Acetone as a Carrier Solvent: (Final Report): 

Lab Project Number: 94-12-5627: 1781.1294.6468.440. Unpublished study 

prepared by Springborn Labs, Inc. 68 p. 

43802601 Putt, A. (1995) Metolachlor Technical--The Chronic Toxicity to Daphnia magna

Under Flow-Through Conditions: Lab Project Number: 95-8-6061. Unpublished 

study prepared by Springborn Labs, Inc. 116 p. 

44995903 Sousa, J. (1999) S-Metolachlor CGA-77102--Early Life-Stage Toxicity Test with 

Fathead Minnow (Pimephales promelas): Final Report: Lab Project Number: 108-

99: 1781.6576. Unpublished study prepared by Springborn Labs., Inc. 79 p. 

Relates to L0000473. 

43928906 Beavers, J. (1983) An Acute Oral Toxicity Study in the Mallard with CGA 77102: 

Lab Project Number: 108-219. Unpublished study prepared by Wildlife 

International Ltd. 14 p. 

43928907 Beavers, J. (1983) An Acute Oral Toxicity Study in the Bobwhite with CGA 

77102: Lab Project Number: 108-220. Unpublished study prepared by Wildlife 

International Ltd. 14 p. 

43928908 Beavers, J. (1983) An Eight-Day Dietary LC50 in the Bobwhite Quail with CGA 

77102: Lab Project Number: 108-217. Unpublished study prepared by Wildlife 

International Ltd. 13 p. 

43928909 Beavers, J. (1983) An Eight-Day Dietary LC50 in Mallard Ducks with CGA 

77102: Lab Project Number: 108-218. Unpublished study prepared by Wildlife 

International Ltd. 14 p. 

43928910 Spare, W. (1983) The Acute Toxicity of CGA-77102 Technical to Bluegill 

Sunfish, Lepomis macrochirus: Lab Project Number: 83-E-168B. Unpublished 

study prepared by Biospherics, Inc. 16 p. 
63 

43928911 Collins, M. (1995) CGA-77102--Acute Toxicity to Rainbow Trout (Oncorhynchus 

mykiss) Under Static Conditions: (Final Report): Lab Project Number: 95-9-6117: 

1781.0495.6500.103. Unpublished study prepared by Springborn Labs, Inc. 68 p. 

43928912 Collins, M. (1995) CGA 77102--Acute Toxicity to Daphnids (Daphnia magna) 

Under Static Conditions: (Final Report): Lab Project Number: 95-9-6082: 

1781.0495.6501.110. Unpublished study prepared by Springborn Labs, Inc. 68 p. 

43928929 Hoberg, J. (1995) 5-Day Toxicity to the Freshwater Green Alga, Selenastrum 

capricornutum: CGA 77102: (Final Report): Lab Project Number: 95-8-6031: 

1781.0495.6502.430. Unpublished study prepared by Springborn Labs, Inc. 69 p. 

43928930 Hoberg, J. (1995) 5-Day Toxicity to the Marine Diatom, Skeletonema costatum: 

CGA 77102: (Final Report): Lab Project Number: 95-8-6062: 

1781.0495.6504.450. Unpublished study prepared by Springborn Labs, Inc. 67 p. 

43928931 Hoberg, J. (1995) Toxicity to Duckweed, Lemna gibba: CGA 77102: (Final 

Report): Lab Project Number: 95-8-6068: 1781.0495.6503.410. Unpublished 

study prepared by Springborn Labs, Inc. 71 p. 

43928932 Chetram, R.; Schuster, L. (1995) Tier 2 Seedling Emergence Nontarget 

Phytotoxicity Study Using CGA 77102: Lab Project Number: 95481. Unpublished 

study prepared by ABC Labs, Pan-Ag Div. 180 p. 

43928933 Chetram, R.; Schuster, L. (1995) Tier 2 Vegetative Vigor Nontarget Phytotoxicity 

Study Using CGA 77102: Lab Project Number: 95482. Unpublished study 

prepared by ABC Labs, Pan-Ag Div. 152 p. 

44015602 Taliaferro, L.; Taliaferro, M.; Miller, V. (1996) The Reproductive Toxicity Test of 

CGA-24705 (Metolachlor) in Mallard Ducks (Anas platyrhynchos): Lab Project 

Number: 029409. Unpublished study prepared by EBA, Inc. 262 p. 

44718401 Bew, M.H. (1992) Acute Contact and Oral Toxicity of CGA-24705 to Honeybees. 

October 30, 1992. Laboratory: MAFF Central Science Laboratory, National Bee 

Unit, Warwickshire, England. Lab. Study ID:CC06092. Novartis Crop Protection, 

Inc., Greensboro, NC 

44718402 Candolfi, M. (1997) CGA-77102: Laboratory Oral and Contact Test with the 

Honeybee, Apis Mellifera: Metolachlor: Lab Project Number: 97-137-1008: 525-

96. Unpublished study prepared by Springborn Laboratories (Europe) AG. 42 p. 

44929501 Vial, A. (1991) Report on the Acute Toxicity Test of CGA-51202 to Rainbow 

Trout (Salmo gairdneri): Final Report: Lab Project Number: 918150: 406-91. 

Unpublished study prepared by Ciba-Geigy Limited. 22 p. 

44929502 Vial, A. (1991) Report on the Acute Toxicity Test of CGA-51202 to Common 

Carp (Cyprinus carpio): Final Report: Lab Project Number: 918151: 407-91. 

Unpublished study prepared by Ciba-Geigy Limited. 20 p. 
64 

44929503 Vial, A. (1991) Report on the Acute Toxicity Test of CGA-51202 on (Daphnia 

magna Straus 1820): Final Report: Lab Project Number: 918162: 405-91. 

Unpublished study prepared by Ciba-Geigy Limited. 23 p. 

44929513 Schwab, D. (1997) Evaluating the Effects of CGA-51202 on the Emergence and 

Vegetative Vigor of Non-Target Terrestrial Plants: Final Report: Lab Project 

Number: 43901: 230-97. Unpublished study prepared by ABC Laboratories, Inc. 

69 p. 

44929514 Boeri, R.; Magazu, J.; Ward, T. (1997) Acute Toxicity of CGA-51202 to the 

Duckweed, Lemna Gibba G3: Final Report: Lab Project Number: 1233-NO: 231-

97. Unpublished study prepared by T.R. Wilbury Laboratories, Inc. 31 p. 

44929515 Vial, A. (1991) Report on the Growth Inhibition Test of CGA-51202 to Green 

Algae (Scenedesmus subspicatus): Final Report: Lab Project Number: 918152: 

408-91. Unpublished study prepared by Ciba-Geigy Limited. 23 p. 

44931702 Rufli, H. (1996) Acute Toxicity Test of CGA-354743 (Metabolite of CGA-24705) 

to Rainbow Trout (Oncorhynchus mykiss) in the Static System: Final Report: Lab 

Project Number: 961526: 489-96. Unpublished study prepared by Ciba-Geigy Ltd. 

46 p. 

44931703 Neumann, C. (1996) Acute Toxicity Test of CGA-354743 (Metabolite of CGA24705) to the Cladoceran (Daphnia magna Straus) Under Static Conditions: Final 

Report: Lab Project Number: 961528: 488-96. Unpublished study prepared by 

Ciba-Geigy Ltd. 40 p. 

44931718 Schwab, D. (1997) Evaluating the Effects of CGA-354743 on the Emergence and 

Vegetative Vigor of Non-Target Terrestrial Plants: CGA-354743: Final Report: 

Lab Project Number: 43900: 229-97. Unpublished study prepared by ABC Labs., 

Inc. 69 p. 

44931719 Grade, R. (1997) Growth Inhibition Test of CGA-354743 (Metabolite of CGA24705) to Green Algae (Selenastrum capricornutum) Under Static Conditions: 

Lab Project Number: 971645: 784-97. Unpublished study prepared by Ciba-Geigy 

Ltd. 51 p. 

44931720 Ward, T.; Magazu, J.; Boeri, R. (1999) Toxicity of CGA-354743 to the 

Duckweed, Lemna gibba G3: Final Report: Lab Project Number: 1688-NO: 1145-

98. Unpublished study prepared by T.R. Wilbury Labs., Inc. 29 p. 

44931721 Candolfi, M. (1997) 14-Day Acute Toxicity Test with the Earthworm (Eisenia 

foetida) Based on OECD Guideline #207: CGA-354743: Final Report: Lab 

Project Number: 97-162-1008: 527-96. Unpublished study prepared by 

Springborn Labs., AG. 47 p. 

44995901 Kaczor, M.; Miller, V. (1999) The Reproductive Toxicity Test of CGA-77102 

Technical with the Northern Bobwhite (Colinus virginianus): Final Report: Lab 

Project Number: 029901: 193-99. Unpublished study prepared by EBA Inc. 305 p. 
65 

44995902 Lima, W. (1999) S-Metolachlor CGA-77102--Life-Cycle Toxicity Test with 

Mysid (Mysidopsis bahia): Final Report: Lab Project Number: 106-99: 

1781.6575. Unpublished study prepared by Springborn Labs., Inc. 81 p. Relates to 

L0000473. 

46322101 Palmer, S.; Kendall, T.; Krueger, H. (2004) Metolachlor Technical: A FlowThrough Life-Cycle Toxicity Test with the Cladoceran (Daphnia magna): Final 

Report. Project Number: 568A/101A. Unpublished study prepared by Wildlife 

International, Ltd. 61 p. 

46508901 Temple, D.; Martin, K.; Beavers, J.; et. al. (2005) Metolachlor Technical: A 

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

568/102. Unpublished study prepared by Wildlife International, Ltd. 181 p. 

46829506 Palmer, S.; Kendall, T.; Krueger, H. (2004) CGA-77102: A 96-Hour StaticRenewal Acute Toxicity Test with the Sheepshead Minnow (Cyprinodon 

variegatus): Final Report. Project Number: 528A/126, 240/02, 

528/041603/SHE/96H2/SUB528. Unpublished study prepared by Wildlife 

International, Ltd. 62 p. 

46829507 Palmer, S.; Kendall, T.; Krueger, H. (2004) CGA-77102: A Flow-Through LifeCycle Toxicity Test With the Cladoceran (Daphnia Magna). Project Number: 

528A/130, 241/02, 528/041603/DAP/LC2/OECD/OPPTS/sub528. Unpublished 

study prepared by Wildlife International, Ltd. 79 p. 

46829509 Desjardins, D.; Kendall, T.; Krueger, H. (2003) CGA-77102: A 96-Hour Toxicity 

Test With the Freshwater Diatom (Navicula pelliculosa): Final Report. Project 

Number: 528A/129, 243/02, 528/041603/NAV96/OECD/OPPTS/SUB528. 

Unpublished study prepared by Wildlife International, Ltd. 69 p. 

46829510 Desjardins, D.; Kendall, T.; Krueger, H. (2004) CGA-77102: A 96-Hour Toxicity 

Test With the Freshwater Alga (Anabaena flos-aquae): Final Report. Project 

Number: 528A/128A, 244/02, 528/041603/ANA/OECD/OPPTS/SUB528. 

Unpublished study prepared by Wildlife International, Ltd. 64 p. 

 
66 

Appendix A: Uses and Rate Table for Metolachlor/S-Metolachlor Labels 

Use Method of Application Maximum Application Rate 

Per Crop Cycle (minimum 

application interval)1

Metolachlor (PC Code 108801) 

Beans Broadcast, chemigation, soil 

broadcast, soil incorporated 

13 app at 2.0 lb ai/A 

Corn (unspecified) Broadcast, soil broadcast 23 apps at 2.1 lb ai/A 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

13 app at 2.7 lb ai/A 

Direct Spray 13 app at 1.6 lb ai/A 

Soil treatment NS apps at 1.8 lb ai/A 

Cotton (unspecified) Broadcast, soil broadcast 23 apps at 2.1 lb ai/A 

Chemigation, direct spray, soil band 

treatment, soil incorporated 

32 apps at 1.3 lb ai/A 

Peanuts (unspecified) Broadcast, soil broadcast NS apps at 2.0 lb ai/A 

Soil incorporated NS apps at 1.3 lb ai/A 

Peas (unspecified) Broadcast, chemigation, soil 

broadcast, soil incorporated 

13 app at 2.0 lb ai/A 

Potato, White/Irish 

(or unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 2.7 lb ai/A 

Safflower 

(unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

NS apps at 2.0 lb ai/A 

Sorghum 

(unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

1 app at 1.7 lb ai/A 

Soybeans 

(unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 2.7 lb ai/A 

Soil treatment (surface) NS apps at 2.4 lb ai/A 

Tomato Direct spray, soil band treatment, soil 

broadcast, soil incorporated 

13 app at 2.0 lb ai/A 

S-Metolachlor (PC Code 108800) 

Caneberry subgroup 

13A (blackberry and 

raspberry) 

Soil band treatment 12 app at 1.9 lb ai/A 

Root vegetables 

subgroup 1B (except 

sugar beet) 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

12 app at 1.3 lb ai/A 

Tuberous and corm 

vegetables subgroup 

1C 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

12 app at 1.3 lb ai/A 

Leafy Brassica greens 

subgroup 5B 

Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Melon subgroup 9A Broadcast, chemigation, soil band, 12 app at 1.2 lb ai/A 
67 

soil broadcast 

Alfalfa Chemigation, soil broadcast NS apps at 3.2 lb ai/A 

Asparagus Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.9 lb ai/A 

Beans, beans (driedtype), beans 

(succulent, lima) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

13 app at 1.9 lb ai/A 

Beans (dried-type) Soil treatment 13 app at 1.9 lb ai/A 

Beets (green), beets 

(root), beets 

(unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 1.3 lb ai/A 

Soil band 12 app at 0.64 lb ai/A 

Bell Peppers Broadcast 12 app at 0.95 lb ai/A 

Chemigation, soil treatment (surface), 12 app at 1.3 lb ai/A 

Direct spray, soil broadcast 12 app at 1.6 lb ai/A 

Blackberry Soil band, soil broadcast 12 app at 1.9 lb ai/A 

Blueberry Soil band 12 app at 1.3 lb ai/A 

Broccoli Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Soil band NS apps at 1.2 lb ai/A 

Brussels sprouts Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Bulb vegetables, 

Cabbage, Cabbage 

(Chinese), 

Cauliflower 

Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.3 lb ai/A 

Carrot (Including 

Tops) 

Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.9 lb ai/A 

Celery Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 1.9 lb ai/A 

Direct spray 12 app at 1.3 lb ai/A 

Chard (swiss) Broadcast, chemigation 1 app at 1.3 lb ai/A 

Soil band, soil broadcast 12 app at 0.95 lb ai/A 

Coriander Broadcast, chemigation, soil 

broadcast 

12 app at 0.95 lb ai/A 

Corn (silage) Soil band, soil treatment, soil 

treatment (surface) 

12 app at 2.0 lb ai/A 

Corn (unspecified) Band treatment, direct spray, 

impregnated dry bulk fertilizer, soil 

treatment 

13 app at 1.6 lb ai/A 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

12 app at 2.5 lb ai/A 

Soil band 13 app at 2.4 lb ai/A 

Corn (field) Broadcast, direct spray, soil band, soil 

treatment (surface), soil treatment 

12 app at 2.0 lb ai/A 
68 

Band treatment, Impregnated dry bulk 

fertilizer, soil incorporated 

13

 app at 1.8 lb ai/A 

Corn (pop) Broadcast, soil band, soil treatment 

(surface) 

NS apps at 2.0 lb ai/A 

Corn (sweet) Broadcast, soil band, soil treatment 

(surface) 

12 app at 2.0 lb ai/A 

Band treatment, impregnated dry bulk 

fertilizer, soil incorporated, 

13 app at 1.8 lb ai/A 

Cotton (unspecified) Broadcast, soil broadcast, soil 

treatment 

13 app at 1.6 lb ai/A 

Chemigation, soil band, 23 apps at 1.3 lb ai/A 

Direct spray, soil incorporated 22 apps at 1.3 lb ai/A 

13

 app at 1.3 lb ai/A 

Crops grown for oil Broadcast, soil broadcast, soil 

incorporated 

12 app at 1.3 lb ai/A 

Cucumber Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Currant, Elderberry, 

Gooseberry, 

Huckleberry 

Soil band 12 app at 1.3 lb ai/A 

Eggplant Broadcast, soil broadcast 12 app at 1.3 lb ai/A 

Garlic, Horseradish, 

Leek 

Broadcast, chemigation, soil band, 

soil broadcast 

1 app at 1.3 lb ai/A 

Grasses grown for 

seed 

Chemigation, soil broadcast 1 app at 1.3 lb ai/A 

Leafy Vegetables Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Direct spray 12 app at 0.64 lb ai/A 

Legume vegetables Broadcast, soil broadcast 1 app at 1.5 lb ai/A 

Lentils Broadcast, chemigation, soil 

broadcast, soil incorporated 

13 app at 1.9 lb ai/A 

Loganberry Soil band, soil broadcast 12 app at 1.9 lb ai/A 

Melons, melons 

(water) 

Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.2 lb ai/A 

Okra Chemigation, direct spray, soil band 12 app at 1.9 lb ai/A 

Onion Broadcast, chemigation, soil band, 

soil broadcast 

22 apps at 1.3 lb ai/A (21 

days) 

Soil incorporated, soil treatment 

(surface) 

12 app at 1.3 lb ai/A 

Onions (green) Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.3 lb ai/A 

Ornamental 

Herbaceous Plants 

Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.2 lb ai/A 

Ornamental Lawns 

and Turf, Ornamental 

Broadcast, chemigation, soil 

broadcast 

13 app at 2.5 lb ai/A 
69 

Sod Farm (Turf) 

Ornamentals 

(unspecified) 

Band Treatment NDC 

Broadcast, chemigation, soil 

broadcast 

12,3 app at 2.5 lb ai/A 

Parsnip Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 1.3 lb ai/A 

Peanuts 

(Unspecified) 

Broadcast, band, soil broadcast NS apps at 1.9 lb ai/A 

Soil incorporated, soil treatment 

(surface) 

NS apps at 1.3 lb ai/A 

Peas (Unspecified) Broadcast, Chemigation, soil 

broadcast, soil incorporated 

13 apps at 1.9 lb ai/A 

Pepper Broadcast, chemigation 12 app at 0.95 lb ai/A 

Soil band, soil broadcast 12 app at 1.3 lb ai/A 

Pepper (Chili type) Direct spray, soil broadcast 12 app at 1.6 lb ai/A 

Potato, white/irish (or 

unspecified) 

Broadcast, chemigation, soil 

broadcast 

12 app at 2.5 lb ai/A 

Soil incorporated 12 app at 1.9 lb ai/A 

Pumpkin Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Soil treatment NS app at 1.3 lb ai/A 

Radish Broadcast, chemigation ,soil 

incorporated 

12 app at 1.2 lb ai/A 

Soil broadcast 13 app at 1.3 lb ai/A 

Radish/Daikon 

(chinese), Rutabaga 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 1.3 lb ai/A 

Soil band 12 app at 0.64 lb ai/A 

Raspberry (black, 

red) 

Soil band, soil broadcast 12 app at 1.9 lb ai/A 

Rhubarb Broadcast, chemigation, soil band, 

soil broadcast 

12 app at 1.3 lb ai/A 

Safflower 

(unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

NS apps at 1.9 lb ai/A 

Sesame Broadcast, soil band, soil broadcast 12 app at 1.3 lb ai/A 

Sorghum Soil broadcast, soil treatment 12 app at 1.7 lb ai/A 

Broadcast, band, chemigation, 

impregnated dry bulk fertilizer, low 

volume spray (concentrate) spray, soil 

band, soil incorporated 

13 app at 1.6 lb ai/A 

Soil treatment (surface) 13 app at 1.3 lb ai/A 

Sorghum (silage) Band, broadcast, impregnated dry 

bulk fertilizer, low volume spray 

(concentrate), soil band, soil 

treatment, spray 

13 app at 1.6 lb ai/A +++ 

Direct spray NS apps at 1.1 lb ai/A 

Soil incorporated, soil treatment 23 apps at 1.3 lb ai/A 
70 

(surface) 

Sorghum 

(unspecified) 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment, soil treatment (surface) 

1 app at 1.6 lb ai/A 

Soybeans 

(unspecified) 

Broadcast, soil broadcast, soil 

incorporated 

13 app at 1.6 lb ai/A 

Chemigation, soil band, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

12,3 app at 2.5 lb ai/A 

Direct spray, 1-22 app at 1.3 lb ai/A 

Soybeans (edible, 

edamame) 

Broadcast, chemigation, soil 

broadcast, soil incorporated, soil 

treatment (surface) 

13 app at 1.9 lb ai/A 

Spinach Broadcast, chemigation2, soil 

broadcast2

1 app at 0.95 lb ai/A 

Soil band 12 app at 0.64 lb ai/A 

Squash (winter, 

Hubbard) 

Broadcast, chemigation, soil 

broadcast 

12 app at 1.3 lb ai/A 

Sugar beet Broadcast, chemigation, soil 

broadcast, soil incorporated 

22 app at 1.9 lb ai/A 

Sunflower Broadcast, chemigation, soil 

broadcast, soil incorporated 

NS apps at 1.9 lb ai/A 

Sweet Potato Broadcast, soil broadcast 1 app at 1.3 lb ai/A 

Tomato Direct spray, soil band, soil broadcast, 

soil incorporated, soil treatment 

(surface) 

13 app at 1.9 lb ai/A 

Turnip (greens), 

turnip (root) 

Broadcast, chemigation, soil 

broadcast, soil incorporated 

12 app at 1.3 lb ai/A 

Soil Band 12 app at 0.64 lb ai/A 

NS – Not Specified on the label 

NDC – No Dosage Conversion 

1

 Minimum application interval was not specified unless otherwise noted. 

2

 Number of applications assumed, based on the crop cycle maximum application rate. 

3

 Number of applications assumed, based on the yearly maximum application rate. 

 
71 

Appendix B: Uses and Rate Table for Special Local Needs (SLN) Labels for 

Metolachlor/S-Metolachlor 

Registration # Crop 

Maximum Application Rate (lb ai/A) 

Single (App. 

Method) Annual/Seasonal 

METOLACHLOR (PC CODE 108801) 

LA110008 

Corn (unspecified), Cotton 

(unspecified), Soybeans 

(unspecified) 

2.1 (B,SB) 4 (Annual) 

MS120002 

Corn (unspecified), Cotton 

(unspecified), Soybeans 

(unspecified) 

2.1 (B,SB) 4 (Annual) 

S-METOLACHLOR (PC CODE 108800) 

AL100003 Sesame 1.3 (B,BA,SB) 1.3 (Seasonal) 

AR030011 Spinach 0.64 (SB) NS 

AR080017

Corn (unspecified), Cotton 

(unspecified), Soybeans 

(unspecified) 

1.6 (B,SB) 2.5 (Annual) 

ARll0004 Sweet Potato 1.3 (B,SB) NS 

AR130013 Soybeans (unspecified) , 

Corn (Unspecified) 

1.3 (B, SB) 2.5 (Seasonal) 

AZI20006 Spinach 0.64 (C,B,SB) NS 

CA010022 Bell Peppers, Pepper (Chili 

Type) 

1.6 (D, SB) 1.6 (Seasonal) 

CA030004 Tomato 1.6 (D,BA,SI,S) NS 

CA060019 Chard (Swiss) 1.3 (B,C,SB) NS 

CA080006 Spinach 0.95 (B, SB,C) NS 

CA080017 Onion 1.3 (SB, BA, B, C) 2.5 

CA080019 Celery 1.9 (B, C, SB, SI) 

1.3 (D) 

1.9 (Seasonal) 

1.9 (Seasonal) 

CAI00004

Root Vegetables (except 

sugar beet), Tuberous and 

Corm Vegetables 

1.3 (SB, SI, S) 1.3 (Seasonal) 

C0030008 Spinach 0.64 (SB, BA) NS 

C0990002 Onion 1.3 (SB, BA) 2.5 

DE030005 Spinach 0.64 (SB) NS 

DE040004 Asparagus 1.9 (B, C, BA, SB) NS 

DEI I OOO I Melons, water 1.2 (C, BA, SB) 1.2 (Seasonal) 

FL110007 

Root Vegetables (except 

sugar beet), Tuberous and 

Corm Vegetables 

1.3 (SB, B, C) 1.3 (Seasonal) 

GA090001

Onion, Onions (Green) 1.3 (SB, B) 2.5 (Annual) 

1.3 (Seasonal) 

Broccoli 1.3 (SB, B) NS 
72 

1.2 (BA) 

Cabbage (Chinese), 

Cauliflower 

1.3 (B, BA, SB) 

1.2 (BA) 

0.95 (SB, B) 

NS 

Bell Peppers 0.95 (B, SB) 0.95 (Seasonal) 

ID020001 Alfalfa 3.2 (C, SB) NS 

ID99001 6 Onion 1.3 (SB, B) 2.5 (Annual) 

IL070005 Soybean 1.3 (SB, B) 2.5 (Annual) 

IL100003 Cabbage 1.3 (B, SB) 1.3 (Seasonal) 

IL14000l Horseradish 1.2 (C, SB) 1.2 (Seasonal) 

IN130003 

Onion 1.3 (SB, BA, B, C) 2.5 (Annual) 

Cabbage 1.3 (B, SB, C) 1.3 (Seasonal) 

Beets (root), Beets 

(unspecified) 

1.2 (B, C, SB, SI) 1.3 (Seasonal) 

Ornamental Herbaceous 

Plants 

1.2 (B, C, SB, BA) 1.3 (Seasonal) 

Coriander, Spinach, 0.95 (B, C, SB) 0.95 (Seasonal) 

Squash (winter)(hubbard) 1.3 (B, C, SB) 1.3 (Seasonal) 

Carrot (including tops) 1.9 (B, C, SB) 1.9 (Seasonal) 

Pepper 1.3 (SB) 

0.95 (B, C) 

1.3 (Seasonal) 

0.95 (Seasonal) 

Cucumber, Leafy Vegetables 1.3 (B, C, SB) 1.3 (Seasonal) 

Blackberry, Loganberry, 

Raspberry (black, red) 

1.9 (SB, BA) 1.9 (Seasonal) 

Bulb Vegetables 1.3 (B, C, BA, SB) 1.3 (Seasonal) 

Currant, Elderberry, 

Gooseberry, Huckleberry, 

Blueberry 

1.3 (BA) 1.3 (Seasonal) 

Melons, Radish 1.2 (B, C, BA, SB) 1.2 (Seasonal) 

Okra 1.9 (D, BA) 1.9 (Seasonal) 

Turnip (Root), Turnip 

(Greens) 

1.3 (B, C, SB, SI) 1.3 (Seasonal) 

KS100001 Sesame 1.3 (B,BA,SB) 1.3 (Seasonal) 

LA1 30008 Soybeans (unspecified), Corn 

(unspecified) 

1.3 (B, SB) 2.5 (Seasonal) 

ME140002

Bell Peppers 1.6 (SB) 

0.95 (B) 

1.6 (Seasonal) 

0.95 (Seasonal) 

Spinach 0.95 (B, SB) NS 

Asparagus 1.9 (B, C, BA, SB) NS 

Cabbage, Onion (Green) 1.3 (B, SB) NS 

Onion 1.3 (B, C, SB, SI, S) 2.5 (Seasonal) 

Pumpkin 1.3 (C, B, SB) 1.3 

Chard (swiss) 0.95 (B, C, BA, SB) 1.33 (Annual) 

Beets (Greens) 0.64 (B, C, BA, SB) 0.64 (Seasonal) 
73 

Carrot (Including Tops) 1.9 (B, C, SB) 1.9 (Seasonal) 

MI110004

Onion 1.3 (SB, BA, B, C) 2.5 (Annual) 

Celery 1.9 (B, C, SB, SI) 1.9 (Seasonal) 

Cabbage 1.3 (B, SB, C) 1.3 (Seasonal) 

Squash (winter)(hubbard) 1.3 (B, C, SB) 1.3 (Seasonal) 

Carrot (including tops) 1.9 (B, SB, C) 1.9 (Seasonal) 

Blueberry 1.3 (BA) 1.3 (Seasonal) 

Spinach 0.95 (B, SB, C) 0.95 (Seasonal) 

Pepper 1.3 (SB) 

0.95 (B, C) 

1.3 (Seasonal) 

0.95 (Seasonal) 

Cucumber 1.3 (B, C, SB) 1.3 (Seasonal) 

Blackberry, Loganberry 1.9 (SB, BA) 1.9 (Seasonal) 

Bulb Vegetables 1.3 (B, C, BA, SB) 1.3 (Seasonal) 

Currant, Elderberry, 

Gooseberry, Huckleberry 

1.3 (BA) 1.3 (Seasonal) 

Melons 1.2 (B, C, BA, SB) 1.2 (Seasonal) 

Okra 1.9 (D, BA, C) 1.9 (Seasonal) 

Raspberry (black,red) 1.9 (SB, BA) 1.9 (Seasonal) 

Leafy Vegetables, Broccoli, 

Brussels sprouts, Cabbage 

(Chinese), Cauliflower 

1.3 (B, C, SB) 1.3 (Seasonal) 

Turnip (Root) 1.3 (B, C, SB, SI) 1.3 (Seasonal) 

Asparagus 1.9 (BA, B, C, SB) 1.9 (Seasonal) 

Chard (Swiss) 0.95 (B, BA, SB, C) 0.95 (Seasonal) 

Radish/Daikon (Chinese), 

Parsnip, Rutabaga 

1.3 (B, C, SB, SI) 1.3 (Seasonal) 

Eggplants 1.3 (SB, B) 1.3 (Seasonal) 

MN000001 Onion 1.3 (SB, B, C) 2.5 (Annual) 

MN040002 Sugar Beet 1.9 (SI) 3.8 (Seasonal) 

MN080006 Squash (winter)(hubbard) 1.3 (B, C, SB) 1.3 (Seasonal) 

MN090004 Crops Grown for oil 1.3 (B, SB, SI) 1.3 (Seasonal) 

MN12000l Carrot (including tops) 1.9 (B, C, SB) 1.9 (Seasonal) 

MN130001 Beans (Dried-Type) 1.3 (B, C, S) 1.9 (Annual) 

MO040002 Spinach 0.64 (SB) NS 

MS060005 Sweet Potato 1.3 (B,SB) NS 

MS080005 

Corn (unspecified) 

Cotton (unspecified) 

Soybeans (unspecified) 

1.6 (B,SB) 2.5 (Annual) 

MS 120001 Soybeans (unspecified) 1.3 (B, SB) 2.5 (Seasonal) 

NC060002 Sweet Potato 1.3 (B,SB) NS 

NCII0005 Bell Peppers 0.95 (SB) 0.95 (Seasonal) 

ND040001 Soybean 1.3 (SB, B) 2.5 (Annual) 

ND I30003 Beans (Dried-Type) 1.3 (B, C, S) 1.9 (Annual) 
74 

NJIIOOI2

Onion 1.3 (BA, SB, B) 2.5 (Annual) 

1.3 (Seasonal) 

Onions (Greens) 1.3 (BA, C) 1.3 (Seasonal) 

Cabbage 1.3 (BA, SB, C) NS 

Carrot (including tops), 

Asparagus 

1.9 (B, C, SB, BA) 1.9 (Seasonal) 

Blueberry 1.3 (BA) 1.3 (Seasonal) 

Pepper 1.3 (SB, BA) 1.3 (Seasonal) 

Chard (Swiss) 0.95 (B, BA, SB, C) 0.95 (Seasonal) 

Spinach 0.64 (SB) 0.64 (Annual) 

Leek 1.3 (B, C, BA, SB) 1.3 (Seasonal) 

NM000001 Onion 1.3 (SB,B) 2.5 

NM990002

Bell Peppers 0.95 (SB) 0.95 (Seasonal) 

Pepper (Chili Type), Bell 

Peppers 

1.3 (D) 1.3 (Seasonal) 

NV990006 Alfalfa 3.2 (C, SB) NS 

NY050001

Bell Peppers 1.6 (SB) 

0.95 (B) 

1.6 (Seasonal) 

0.95 (Seasonal) 

Asparagus 1.9 (B, C, BA, SB) NS 

Cabbage 1.3 (B, SB) NS 

Onion (Green) 1.3 (B, C, SB, BA) NS 

Onion 1.3 (B, C, SB, BA) 

1.3 (B, C, SB, SI, S) 

NS 

2.55 (Seasonal) 

Pumpkin, Squash (Winter) 

(Hubbard) 

1.3 (C, B, SB) 1.3 (Seasonal) 

Chard (swiss) 0.95 (C, B, BA, SB) 1.33 (Annual) 

Beets (Greens) 0.64 (B, C, BA, SB) 0.64 (Seasonal) 

Carrot (Including Tops) 1.9 (B, C, SB, BA) 1.9 (Seasonal) 

Spinach 0.64 (BA) 0.64 (Seasonal) 

NY110004

Broccoli 1.3 (B, SB) NS 

Blueberry 1.3 (BA) 1.3 (Seasonal) 

Cucumber, Leafy Brassica 

Greens 

1.3 (B, C, SB) 1.3 (Seasonal) 

Caneberry (blackberry and 

raspberry) 

1.9 (BA) 1.9 (Seasonal) 

Melon Subgroup 1.2 (B, C, BA, SB) 1.2 (Seasonal) 

Garlic 1.3 (B, C, BA, SB) NS 

OH110002

Onion, Bulb Vegetables 1.3 (SB, BA, B,C) 2.5 (Annual) 

Cabbage, Squash 

(winter)(hubbard) 

1.3 (B, SB, C) 1.3 (Seasonal) 

Carrot (including tops) 1.9 (B, C, SB) 1.9 (Seasonal) 

Spinach 0.95 (B, SB, C) 0.95 (Seasonal) 

Pepper 1.3 (SB) 

0.95 (B, C) 

1.3 (Seasonal) 

0.95 (Seasonal) 

Cucumber, Leafy Vegetables 1.3 (B, C, SB) 1.3 (Seasonal) 
75 

Blackberry, Loganberry, 

Raspberry (black,red) 

1.9 (SB, BA) 1.9 (Seasonal) 

Currant, Elderberry, 

Gooseberry, Huckleberry, 

Blueberry 

1.3 (BA) 1.3 (Seasonal) 

Melons 1.2 (B, C, BA, SB) 1.2 (Seasonal) 

Okra 1.9 (D, BA) 1.9 (Seasonal) 

Turnip (Root), Turnip 

(Greens), Beets (Greens) 

1.3 (B, C, SB, SI) 1.3 (Seasonal) 

Radish 1.2 (B, C, SB, SI) 1.2 (Seasonal) 

OK020003 Pepper 0.95 (SB) 

NS (C) 

NS 

NS 

OK030002 Spinach 0.64 (SB) NS 

OKI00002 Sesame 1.3 (B, BA, SB) 1.3 (Seasonal) 

OK110001 Sweet Potato 1.3 (B,SB) NS 

OR040010 Radish 1.3 (SB) 1.3 (Annual) 

OR060012

Carrot (Including Tops) 1.9 (B, C, SB, BA) 1.9 (Seasonal) 

Beets (Greens), Parsnip, 

Radish/Daikon (Chinese), 

Rutabaga, Turnip (Greens), 

Turnip (Root) 

0.64 (B, C, BA, SB) 0.64 (Seasonal) 

OR110005 Blueberry 1.3 (BA) 1.3 (Seasonal) 

Raspberry (black,red) 1.9 (BA) 1.9 (Seasonal) 

PA080002

Spinach 0.95 (B, SB) NS 

Onion, Cabbage 1.3 (SB, BA,B) 2.5 (Annual) 

1.3 (Seasonal) 

Bell Peppers 0.95 (B, SB) 0.95 (Seasonal) 

SC070002 Spinach 0.64 (B, SB) NS 

TN110004

Leafy Vegetables 1.3 (B, C, SB) 

0.64 (D) 

1.3 (Seasonal) 

0.64 (Seasonal) 

TN130004 Soybeans (unspecified), Corn 

(unspecified) 

1.3 (B, SB) 2.5 (Seasonal) 

TX040011 Cotton (Unspecified) 1.3 (B, C, SB) NS 

TX070003

Onion 1.3 (SB, BA, B) 2.5 (Annual) 

Onions (Greens) 1.3 (BA) 1.3 (Seasonal) 

Cabbage, Beets (Greens) 1.3 (B, SB) 1.3 (Seasonal) 

Pepper 1.3 (SB) 

0.95 (B) 

1.3 (Seasonal) 

0.95 (Seasonal) 

Sweet Potato 0.95 (B, SB) 0.95 (Seasonal) 

TX080006 Pumpkin 1.3 (B, SB) 1.3 (Seasonal) 

Chard (Swiss) 0.95 (B, BA, SB) 0.95 (Seasonal) 

TX100008 Sesame 1.3 (B, BA, SB) 1.3 (Seasonal) 

TX100013 Spinach 0.64 (B, SB) NS 

TX100014 Beans (Succulent, lima) 1.9 (B, SB, SI) 1.9 (Annual) 
76 

VA030003 Spinach 0.64 (B, SB, BA) NS 

VA110006 Melons, water 1.2 (C, BA, SB) 1.2 (Seasonal) 

VA990001 Onion 1.3 (SB,B) 2.5 (Annual) 

VA990002 Cabbage 1.3 (B, SB) 1.3 (Seasonal) 

Bell Peppers 1.3 (D, C, S) 1.3 (Seasonal) 

WA120001 Chard (swiss) 0.95 (B, SB, BA) 1.33 (Annual) 

Beets (Greens) 0.64 (B, SB) 0.64 (Annual) 

WA120002 

Blueberry 1.3 (BA) 1.3 (Seasonal) 

Blackberry, Raspberry 

(black,red) 

1.9 (BA) 1.9 (Seasonal) 

WI130001

Onion 1.3 (SB, BA, B,C) 2.5 (Annual) 

1.3 (Seasonal) 

Onions (Greens) 1.3 (BA, C) 1.3 (Seasonal) 

Celery 1.9 (B, C, SB, SI) 1.9 (Seasonal) 

Cabbage 1.3 (B, SB, C) 1.3 (Seasonal) 

Carrot (including tops) 1.9 (B, C, SB) 1.9 (Seasonal) 

Spinach 0.95 (B, SB, C) 0.95 (Seasonal) 

Pepper 1.3 (SB) 

0.95 (B, C) 

1.3 (Seasonal) 

0.95 (Seasonal) 

Cucumber 1.3 (B, C, SB) 1.3 (Seasonal) 

Turnip (Root), Turnip 

(Greens), Beets (Greens), 

Radish/Daikon (Chinese), 

Parsnip, Rutabaga 

1.3 (B, C, SB, SI) 1.3 (Seasonal) 

Chard (Swiss) 0.95 (B, BA, SB, C) 0.95 (Seasonal) 

Broccoli, Brussels sprouts, 

Cabbage (Chinese), 

Cauliflower 

1.3 (B, C, SB,) 1.3 (Seasonal) 

Eggplants 1.3 (SB, B) 1.3 (Seasonal) 

Leek 1.3 (B, C, BA, SB) 1.3 (Seasonal) 

WY110001 Radish 1.3 (SB) 1.3 (Annual) 

NS: Not Specified 

Application Methods: 

B: Broadcast SB: Soil Broadcast BA: Band Treatment C: Chemigation 

SI: Soil Incorporated S: Soil Treatment (Surface) D: Directed Spray 

 
77 

Appendix C: Previous Actions and Assessed Uses for Metolachlor/SMetolachlor 

Use Site Max. Application Rate 

(lb ai/A) 

Number of 

Applications 

(Application 

Interval in 

Days) 

Action/DP 

Barcode/Date 

Comments 

Single 

(App 

Method) 

Seasonal/ 

Annual 

Metolachlor (PC Code 108801) 

N/A N/A N/A N/A Revised TRED DWA 

D238805 +9 more 

5/22/2002 

Tomatoes 1.5-3.0 NS NS Section 18 

Emergency Exemption 

Pennsylvania 

D234833 

4/22/1997 

Spinach 0.75-1.0 

(G,A) 

0.75-1.0 1 Section 18 

Emergency Exemption 

Virginia 

D221250 

1/17/1996 

Not likely to affect non-listed 

or listed animal populations. 

Agency LOCs exceeded for 

terrestrial and aquatic plants. 

Spinach 1 (G) 

2 (I) 

3 2 (NS) Section 18 

Emergency Exemption 

Texas 

8/2/1995 

Agency LOCs exceeded for 

terrestrial and aquatic plants. 

Spinach 1.0 (G) 1 1 Section 18 

Emergency Exemption 

New Jersey 

D213744 

4/20/1995 

Agency LOCs exceeded for 

terrestrial and aquatic plants. 

Spinach 1.0 (G) 1 1 Section 18 

Emergency Exemption 

Louisiana 

D208252 

1/10/1995 

Spinach 1.0 (G) 1 1 Section 18 

Emergency Exemption 

Arkansas 

D208746 

1/10/1995 

Spinach 1.0 (G) 1 1 Section 18 

Emergency Exemption 

Maryland 

8/19/1994 

Spinach 1.0 (G) 1 1 Section 18 

Emergency Exemption 

Oklahoma 

D198582 

2/15/1994 

All Uses N/A N/A N/A RED 

D185152, D172022 

6/30/1993 

Ecological Effects Branch 

Review 
78 

All Uses N/A N/A N/A RED 

D185152, D172022 

3/1/1993 

Environmental Fate and 

Ground Water Branch Review 

Cabbage 2 (G) 2 1 Section 18 

Emergency Exemption 

New York 

5/31/1988 

Cabbage 2 (G) 2 1 Section 18 

Emergency Exemption 

Wisconsin 

3/10/1988 

Dry Bulb 

Onions 

2 (G) 4 2 (NS) Section 18 

Emergency Exemption 

Wisconsin 

1/9/1987 

Cabbage 2 (G) 2 1 Section 18 

Emergency Exemption 

New York 

2/24/1987 

Proposed use will have minimal 

adverse effects on listed 

species. 

Dry Bulb 

Onions 

2 (G) 4 2 (NS) Section 18 

Emergency Exemption 

Michigan 

1/9/1987 

Proposed use will have minimal 

adverse effects on listed 

species. 

Cole crops 

(cabbage, 

broccoli, 

collards) 

1.5-2.0 

pints/A 

NS NS Section 18 

Emergency Exemption 

Florida 

10/2/1981 

Sunflower, 

Flax 

2.5-3 NS NS Section 3 

New Use 

10/27/1980 

Use Site: potatoes, sorghum, 

right of ways, peanuts, 

soybeans, field corn 

S- Metolachlor (PC Code 108800) 

Cilantro, 

Garden 

beet leaves 

0.96 (G) 

1.27 (G) 

0.96 

1.27 

1 

1 

Section 3 

New minor uses 

D392602 

1/4/2012 

LOC exceedances for birds and 

freshwater aquatic invertebrates 

from chronic exposure, 

terrestrial and aquatic plants 

and mammals from chronic 

exposure. 

Cilantro, 

Garden 

beet leaves 

0.96 (G) 

1.27 (G) 

0.96 

1.27 

1 

1 

DWA 

D392449 

11/11/2011 

Lettuce 0.95 (G) 

(per crop) 

0.95 1 Section 18 

Emergency Exemption 

Michigan 

D390436 

6/22/2011 

Various IR4 Uses 3.81 (G) 1 3.81 1 Section 3 

New minor uses 

D370759 

6/23/2010 

Uses include: sesame, melon, 

bushberry, caneberry, sorghum, 

leafy brassica, turnip greens, 

carrot,, cucumber, okra, dry 

bulb onions and green onion. 

LOC exceedances for chronic 

risk to freshwater fish, 

invertebrates and acute risk to 
79 

vascular and nonvascular 

aquatic plants for all uses. 

Various IR4 Uses 

(max rate is 

caneberry) 

3.81 (G) 1 3.81 1 DWA 

D368735 

4/22/2010 

Sesame 1.27 

(G,A) 

1.27 1 Section 18 

Emergency Exemption 

Oklahoma, Texas 

D367230, D367228 

9/15/2009 

Ecological risk are to terrestrial 

and aquatic plants. 

Leafy 

Greens, 

Herbs 

1.27 (G) 1.27 1 Section 18 

Emergency Exemption 

Ohio 

D329114 

5/31/2006 

Pumpkin, 

Winter 

Squash 

1.27 (G) 1.27 1 Section 3 

New minor uses 

D324973, D327861 

5/31/2006 

Non-listed and listed terrestrial 

plant LOCs are exceeded. 

Pumpkin, 

Winter 

Squash 

1.27 (G) 1.27 1 DWA 

D324967 

3/20/2006 

Assessment conclusions drawn 

from DWA for corn. 45845 

Various IR4 Uses

2.5 (A)1

 2.5 1 DWA 

D296726 

6/16/2004 

IR-4 Uses Include: fruiting 

vegetables, green and dry bulb 

onions, root vegetables (except 

sugarbeets), tuberous and corn 

vegetables, head and stem 

brassica, leaf petioles, Spinach. 

Assessment conclusions drawn 

from 2002 tolerance 

reassessment (TRED; 

D248805). 3401 

Red Beets 0.66 

0.33 

0.66 

0.66 

1 

2 

Section 18 

Emergency Exemption 

New York 

D297472 

1/23/2004 

Exceedances for both acute 

listed and non-listed LOC at a 

single and multiple (2) 

applications. 

23834 

Sweet 

Potatoes 

1.27 1.27 1 Section 18 

Emergency Exemption 

Louisiana 

D282660 

5/15/2002 

Acute and chronic exceedances 

for terrestrial plants. 4663-4 

1

 Highest proposed use rate. 

*Value is assumed. 

N/A= Not applicable, NS = Not specified, DWA = Drinking Water Assessment, EFGWB = Environmental Fate and 

Ground Water Branch 

G = ground, A = aerial, I = Irrigation 
80 

Appendix D: Summary of Endpoints from Metolachlor/S-Metolachlor Toxicity S

 Summary of Endpoints from Toxicity Studies with Metolachlor (CGA-24705) 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable)

Avian acute oral: single dose, 8-day observation (instead of usual 14-day observation) 

Metolachlor technical (NS) 

Mallard duck (Anas platyrhynchos) 

LD50 (95% C.I.) = 4640 (3000-7200) mg/kg-bw (nom) 

NOAEC : Not specified Practically non-toxic 

Avian acute oral: single dose, 14-day observation 

Metolachlor technical (NS) 

Mallard duck (Anas platyrhynchos) 

LD50 > 2510 mg/kg-bw (nom) 

NOAEC : Not specified (no treatment-related effects) Practically non-toxic 

Avian acute oral Metolachlor Passerine species No data Avian sub-acute dietary: 5-day exposure; 3-day post-exposure observation 

Metolachlor technical (NS) 

Mallard duck (Anas platyrhynchos)

LC50 > 10,000 mg/kg-diet (nom) 

NOAEC: Not specified (no mortality; sublethal effects: decreased weight gain at ≥4mg/kg-diet; decreased feed consumption at 10,000 mg/kg-diPractically non-toxic 

Metolachlor technical (NS) 

Bobwhite quail (Colinus virginianus) 

LC50 > 10,000 mg/kg-diet (nom) 

NOAEC: Not specified (10% [1/10] mortality at 10,000 mg/kg-diet; sublethal effectwing droop, lethargy, no weight gain, and greatly decreased consumption at 10,000 mg/kg-diet) Practically non-toxic 

Avian reproduction: ~20 weeks (chronic) 

Metolachlor technical (97.2) 

Bobwhite quail (Colinus virginianus) 

NOAEC = 403 mg a.i./kg-diet (mm) LOAEC = 1010 mg a.i./kg-diet (mm) (based on increase in cracked eggs) 

Avian reproduction: 20 weeks (chronic) 

Metolachlor technical (97.3) 

Mallard duck (Anas platyrhynchos) 

NOAEC = 800 mg a.i./kg-diet (nom) LOAEC > 800 mg a.i./kg-diet (nom) (no treatment-related effects) 

Avian reproduction: 22 weeks (chronic) 

Metolachlor technical (97) 

Mallard duck (Anas platyrhynchos) 

NOAEC = 10 mg/kg-diet (nom) LOAEC = 300 mg/kg-diet (nom) (based on adult feed consumption and body weight) 
81 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable)

Mammalian acute oral, limit: single dose; 7-day observation (instead of usual 14-day observation) 

Metolachlor (NS) 

Rat (Rattus norvegicus) 

LD50 (95% C.I.) = 2780 (2180-3545) mg/kg-bw 

(20,30, 50, and 100% mortality at 1670, 2150, 2780, and 464mg/kg-bw ; sublethal effects : dose-dependent increase in sedation, dyspnea, exophthalmos, curved position, trismus, tonic-clonic muscle spasms, and ruffled fur ; surviving animrecovered within 3 to 5 days) Practically non-toxic 

Mammalian acute inhalation 

Metolachlor Rat 

(Rattus norvegicus) 

LC50 > 1.75 mg/L 

Mammalian reproduction (chronic) 

Metolachlor Rat 

(Rattus norvegicus) 

NOAEC = 300 mg a.i./kg-diet (based on reduced pup weights in F1 and F2 litters) 

Acute contact with adult honey bees: single dose, 48-hour observation 

Metolachlor (97) 

Adult honey bee (Apis mellifera)

LD50 > 110 μg a.i./bee (nom) 

NOAEL = 110 μg a.i./bee (nom) (no control mortality ; 0-5% mortality across 4 treatment concentrations) Practically non-toxic 

Acute oral with adult honey bees: single dose, 48-hour observation 

Metolachlor (97) 

Adult honey bee (Apis mellifera) 

LD50 > 110 μg a.i./bee (nom) 

NOAEL = 110 μg a.i./bee (nom) (no control mortality ; 0-7.5% mortality across 4 treatment concentrations) Practically non-toxic 

Acute oral with honey bee larvae 

NA Larval honey bee No data 

Chronic oral with honey bee adults 

NA Adult honey bee No data 

Chronic oral with honey bee larvae 

NA Larval honey bee No data 

Terrestrial plant seedling emergence: 21 days 

Metolachlor technical (97.3) 

Most sensitive monocot: Ryegrass 

EC25 (95% C.I.) = 0.02 (0.017-0.033) lb a.i./A 

NOAEC = 0.0031 lb a.i./A  (based on dry weight, height) 

Most sensitive dicot: Lettuce 

Lettuce: EC25 (95% C.I.) = 0.09 (0.012-0.62) b a.i./A 

NOAEC = 0.012 lb a.i./A  (based on dry weight) 
82 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable)Note: Lettuce also had an EC25 of 0.09 lb a.i./A for dry weig

but the associated NOAEC of 0.049 lb a.i./A was slightly higher. 

Terrestrial plant vegetative vigor: 21 days 

Metolachlor technical (97.3) 

Most sensitive monocot: Ryegrass 

EC25 = 0.016 lb a.i./A 

NOAEC = 0.0031 lb a.i./A  (based on dry weight) 

Most sensitive dicot: Cucumber 

EC25 (95% C.I.) = 0.030 (0.020-0.046) lb a.i./A 

NOAEC = 0.025 lb a.i./A  (based on dry weight) 

Freshwater fish acute: 96 hours 

Metolachlor technical (NS) 

Rainbow trout (Salmo gairdneri) 

LC50 (95% C.I.) = 3.80 (3.37-4.27) mg/L (nom) 

NOAEC: Not specified (no mortality at ≤2.8 mg/L; mortality at ≥4.1 mg/L) Moderately toxic 

Freshwater fish acute: 96 hours 

Technical metolachlor (NS) 

Crucian carp (Carassius carassius) 

LC50 (95% C.I.) = 4.9 (3.6-6.8) mg/L (nom) 

(sublethal effects: hypersensitivity, loss of equilibrium, and apathy at ≥2.1 mg/L) Moderately toxic 

Freshwater fish acute: 96 hours 

Technical metolachlor (NS) 

Channel catfish (Ictalurus punctatus) 

LC50 (95% C.I.) = 4.9 (3.6-6.8) mg/L (nom) 

(sublethal effects: hypersensitivity, loss of equilibrium, and apathy at ≥2.1 mg/L) Moderately toxic 

Freshwater fish acute: 96 hours 

Technical metolachlor (NS) 

Guppy (Lebistes reticulatus) 

LC50 (95% C.I.) = 8.6 (7.4-10.5) mg/L (nom) 

(sublethal effects: hypersensitivity, loss of equilibrium, and apathy at ≥6.5 mg/L) Moderately toxic 

Freshwater fish acute: 96 hours 

Metolachlor technical (NS) 

Bluegill sunfish (Lepomis macrochirus) 

LC50 (95% C.I.) = 10.3 (9.5-11.1) mg/L (nom) 

NOAEC = 6.0 mg/L (nom) LOAEC = 8.8 mg /L (nom) Slightly toxic 
83 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable)

Freshwater fish acute: 96 hours 

Technical metolachlor (NS) 

Bluegill sunfish (Lepomis macrochirus) 

LC50 = 15 mg/L (nom) 

(no mortality at ≤10 mg/L; sublethal effects: hypersensitivityloss of equilibrium, and apathy at concentration where mortaoccurred) Slightly toxic 

Freshwater fish early life stage 

Metolachlor Freshwater species No data 

Estuarine/marine fish acute: 96 hours, flow through 

Metolachlor technical (97.3) 

Sheepshead Minnow (Cyprinodon variegatus) 

LC50 (95% C.I.) = 9.8 (8.5-11.5) mg a.i./L (mm) 

NOAEC = 3.6 mg a.i./L (mm) LOAEC = 6.2 mg a.i./L (mm) (sublethal effects: lethargy and loss of equilibrium were observed among all surviving fish at 11 mg/L and to one fish 6.2 mg/L) Moderately toxic 

Estuarine/marine fish acute: 96 hours, flow through 

Metolachlor technical (97) 

Sheepshead Minnow (Cyprinodon variegatus) 

LC50 (95% C.I.) = 7.9 (4.4-∞) mg/L (mm) 

NOAEC: Not specified (no mortality at ≤4.4 mg/L; 70% mortality at 9.4 mg/L) Moderately toxic 

Estuarine/marine fish early life stage (chronic): 26 days, flow through 

Metolachlor technical (97) 

Sheepshead Minnow (Cyprinodon variegatus) 

NOAEC = 1.0 mg/L (mm) LOAEC = 2.2 mg/L (mm) (NOAEC based on most sensitive endpoint of reduced lengthsurvival and hatch also affected) 

Freshwater invertebrate acute: 48 hours, static 

Metolachlor (Not reported) 

Water flea (Ceriodaphnia dubia) 

EC50 (95% C.I.) = 1.1 (0.9-1.4) mg/L 

Moderately toxic 

Freshwater invertebrate acute: 48 hours 

Metolachlor technical (NS) 

Water flea (Daphnia magna) 

EC50 (95% C.I.) = 25.1 (21.6-29.2) mg a.i./L 

NOAEC = 5.6 mg a.i./L LOAEC = 10 mg a.i./L (NOAEC based no mortality at 5.6 mg/L) Slightly toxic 

Freshwater invertebrate life 

Metolachlor (Not reported) 

Water flea (Daphnia magna) 

NOAEC = 0.001 mg/L (nom) LOAEC = 0.01 mg/L (nom) (based on number of young per female) 
84 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable)

cycle: 21 days, static renewal Freshwater invertebrate life cycle: 21 days, flow through (chronic) 

Metolachlor technical (97.2) 

Water flea(Daphnia magna) 

NOAEC = 4.9 mg a.i./L (mm) LOAEC = 9.4 mg a.i./L (mm) (NOAEC based reductions in growth [length] and reproduct

Freshwater invertebrate life cycle: 21 days, flow through (chronic) 

Metolachlor technical (97) 

Water flea(Daphnia magna)

NOAEC = 3.2 mg a.i./L (m) LOAEC = 6.9 mg a.i./L (m) (NOAEC based reductions in growth and reproduction) Note: Due to variability in the measured concentrations, the endpoints are based on the lowest measured concentration at each treatment level. 

Estuarine/marine invertebrate acute: 96 hours, flow through 

Metolachlor technical (97.3) 

Mysid shrimp(Mysidopsis bahia)

EC50 (95% C.I.) = 4.95 (4.21-5.94) mg a.i./L (mm) 

Probit slope (95% C.I.) = 6.1 (3.5-8.6) NOAEC = 2.3 mg a.i./L (mm) LOAEC = 4.0 mg a.i./L (mm) (NOAEC based on no mortality at ≤2.3 mg/L; surviving daphnids at 4.0 and 7.1 mg/L exhibited dark pigmentation anlethargy) Moderately toxic 

Estuarine/marine mollusc acute: 96 hours, flow through, shell deposition 

Metolachlor technical (97.3) 

Eastern oyster (Crassostrea virginica) 

EC50 (95% C.I.) = 1.6 (1.4-1.9) mg a.i./L (mm) 

NOAEC = 0.71 mg a.i./L (mm) LOAEC = 1.1 mg a.i./L (mm) (sublethal effects: reduction in feeding and fecal and pseudofecal production were observed at all observation intervals at the highest treatment level, 4.5 mg/L) Moderately toxic 

Estuarine/marine invertebrate life cycle 

Metolachlor Estuarine/marine 

species 

No data 

Benthic freshwater invertebrate 

Metolachlor Freshwater species No data 
85 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable)

Benthic estuarine/marine invertebrate 

Metolachlor Estuarine/marine 

species 

No data 

Aquatic vascular plant: 14 days, static 

Metolachlor technical (97.3) 

Duckweed (Lemna gibba)

EC50 (95% C.I.) = 0.048 (0.043-0.056) mg a.i./L (im) 

NOAEC = 0.0084 mg a.i./L (im) LOAEC = 0.015 mg a.i./L (im) (based on frond number; sublethal effects: little root formatismaller fronds, and chlorosis at 0.058 mg/L, compared to the control; slight chlorosis at 0.0084 to 0.030 mg/L; several chlorotica fronds in control and at 0.0011 to 0.0042 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Green alga (Selenastrum capricornutum) 

EC50 (95% C.I.) = 0.010 (0.006-0.020) mg a.i./L (mm) 

NOAEC = 0.0007 mg a.i./L (mm) LOAEC = 0.0014 mg a.i./L (mm) (based on cell density; bloated cells and cell fragments at ≥0.0025 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Marine diatom (Skeletonema costatum) 

EC50 (95% C.I.) = 0.061 (0.049-0.076) mg a.i./L (mm) 

NOAEC = 0.0017 mg a.i./L (mm) LOAEC = 0.0048 mg a.i./L (mm) (based on cell density; sublethal effects: cell fragments and bloated cells at ≥ 0.15 mg/L; thin cell walls at ≥ 0.56 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Freshwater diatom (Navicula pelliculosa) 

EC50 (95% C.I.) = 0.38 (0.27-0.56) mg a.i./L (mm) 

NOAEC = 0.0037 mg a.i./L (mm) LOAEC = 0.013 mg a.i./L (mm) (based on cell density; sublethal effects: bloated cells and cefragments at ≥ 0.13 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

Metolachlor technical (97.3) 

Cyanobacterium (Anabaena flos-aquae) 

EC50 (95% C.I.) = 1.2 (0.9-1.6) mg a.i./L (mm) 

NOAEC = 0.063 mg a.i./L (mm) LOAEC = 0.19 mg a.i./L (mm) (based on cell density; cell fragments at ≥0.72 mg/L; bloated 

cells at 6.8 mg/L) 

Abbreviations: C.I. = confidence interval; form. = formulation; im = initial measured; mm = mean measured; nom = nominal; NA = nospecified; TEP = typical end-use product; TWA = time-weighted average 
86 

 Summary of Endpoints from Toxicity Studies with S-Metolachlor (CGA-77102) 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Avian acute oral: single dose, 14-day observation 

S-Metolachlor technical (87.4) 

Mallard duck (Anas platyrhynchos) 

LD50 > 2194 mg a.i./kg-bw (m) 

NOAEC = 2194 mg a.i./kg-bw (m) (no sublethal effects or treatment-related mortality) Practically non-toxic 

Avian acute oral: single dose, 14-day observation 

S-Metolachlor technical (87.4) 

Bobwhite quail (Colinus virginianus) 

LD50 > 2194 mg a.i./kg-bw (m) 

NOAEC = 874 mg a.i./kg-bw (m) LOAEC = 1390 mg a.i./kg-bw (m) (no mortality; body weight losses at ≥1390 mg/kg-bw) Practically non-toxic 

Avian acute oral Metolachlor Passerine species No data Avian sub-acute dietary: 5-day exposure; 3-day post-exposure observation 

S-Metolachlor technical (87.4) 

Mallard duck (Anas platyrhynchos)

LC50 > 4912 mg/kg-diet (m) 

NOAEC = 1556 mg a.i./kg-diet (m) LOAEC = 2762 mg a.i./kg-diet (m) (20% [2/10] mortality at 874 mg/kg-diet; NOAEC based on slight reduction in body weight gain at ≥2762 mg/kg-diet du

the first 5 days of the test) Practically non-toxic 

S-Metolachlor technical (87.4) 

Bobwhite quail (Colinus virginianus) 

LC50 > 4912 mg/kg-diet (m) 

NOAEC = 2762 mg a.i./kg-diet (m) LOAEC = 4912 mg a.i./kg-diet (m) (no mortality; NOAEC based on slight reduction in body wegain at 4912 mg/kg-diet during the first 5 days of the test) Practically non-toxic 

Avian reproduction: 24 weeks (chronic) 

S-Metolachlor (98.6) 

Bobwhite quail (Colinus virginianus) 

NOAEC = 1000 mg a.i./kg-diet (nom) LOAEC > 1000 mg a.i./kg-diet (nom) (no effects) 

Mammalian acute oral 

S-Metolachlor Rat 

(Rattus norvegicus) 

Combined sexes LD50 = 3267 mg/kg-bw 

Male LD50 = 2577 mg/kg-bw 

Female LD50 = 2672 mg/kg-bw 

Practically n0n-toxic 
87 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Mammalian acute inhalation 

S-Metolachlor Rat 

(Rattus norvegicus) 

LC50 > 2.91 mg/L 

Mammalian reproduction (chronic) 

S-Metolachlor Rat 

(Rattus norvegicus) 

No data 

Acute contact with adult honey bee: single dose, 72-hour observation 

S-Metolachlor (98.5) 

Adult honey bee (Apis mellifera)

LD50 > 200 μg a.i./bee (nom) 

NOAEL = 200 μg a.i./bee (nom) (no control mortality ; 10% mortality at limit dose) Practically non-toxic 

Acute oral with adult honey bee, limit: single dose, 72-hour observation 

S-Metolachlor (98.5) 

Adult honey bee (Apis mellifera) 

LD50 > 85 μg a.i./bee (nom) 

NOAEL = 85 μg a.i./bee (nom) (3% control mortality ; 3-10% mortality across 9 treatment levels) Practically non-toxic 

Acute oral with honey bee larvae 

NA Larval honey bee No data 

Chronic oral with honey bee adults 

NA Adult honey bee No data 

Chronic oral with honey bee larvae 

NA Larval honey bee No data 

Terrestrial plant seedling emergence: 21 days 

S-Metolachlor technical (97.6) 

Most sensitive monocot: Ryegrass 

EC25 = 0.0048 lb a.i./A 

NOAEC = 0.0010 lb a.i./A (based on phytotoxicity) 

Most sensitive dicot: Lettuce 

EC25 (95% C.I.) = 0.0057 (0.0011-0.0308) lb a.i./A 

NOAEC = 0.0003 lb a.i./A  (based on dry weight) 

Terrestrial plant vegetative vigor: 21 days 

S-Metolachlor technical (97.6) 

Most sensitive monocot: Ryegrass 

EC25 (95% C.I.) = 0.021 (0.012-0.037) lb a.i./A 

NOAEC = 0.011 lb a.i./A  (based on dry weight) 

Most sensitive dicot: Cucumber 

EC25 (95% C.I.) = 0.27 (0.12-0.65) lb a.i./A 

NOAEC = 0.30 lb ai.i./A EC05 = 0.01 lb a.i./A Note: Since the NOAEC > EC25, the EC05 will be used for 

assessing risk to listed species. 
88 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) (based on phytotoxicity) 

Freshwater fish acute: 96 hours, static 

S-Metolachlor technical (Not reported) 

Bluegill sunfish (Lepomis macrochirus) 

LC50 (95% C.I.) = 3.2 (2.8-4.6) mg a.i./L (im) 

Probit slope (95% C.I.) = 14.8 (2.1-27.5) NOAEC = 1.5 mg a.i./L (im) LOAEC = 2.59 mg a.i./L (im) (NOAEC based on no mortality or sublethal effects at ≤1.5 mg/L; swimming on surface at ≥3.29 mg/L) Moderately toxic 

Freshwater fish acute: 96 hours, static 

S-Metolachlor (97.6) 

Rainbow trout (Oncorhynchus mykiss) 

LC50 (95% C.I.) = 11.9 (8.3-15) mg a.i./L (mm) 

NOAEC = 2.5 mg a.i./L LOAEC = 5.3 mg a.i./L (mm) (NOAEC based on sublethal effects including partial//complloss of equilibrium, extended abdomen, lethargy, and residinbottom at ≥5.3 mg/L) Slightly toxic 

Freshwater fish early life stage: 30+ days, flow-through 

S-Metolachlor technical (98.6) 

Fathead minnow (Pimephales promelas) 

NOAEC = 0.030 mg a.i./L (mm) LOAEC = 0.056 mg a.i./L (mm) (based on most sensitive endpoint of dry weight; length also affected) 

Estuarine/marine fish acute: 96 hours, static renewal 

S-Metolachlor (98.9) 

Sheepshead minnow (Cyprinodon variegatus) 

LC50 (95% C.I.) = 16.8 (12.1-23.3) mg a.i./L (TWA) 

NOAEC = 6.04 mg a.i./L (TWA) LOAEC = 12.1 mg a.i./L (TWA) (NOAEC based on sublethal effects including discoloration, surfacing ad lying on the bottom of the test vessel at 12.1 mgSlightly toxic 

Estuarine/marine fish early life stage (chronic) 

S-Metolachlor Estuarine/marine 

species 

No data 

Freshwater invertebrate acute: 48 hours, static 

S-Metolachlor technical (97.6) 

Water flea (Daphnia magna) 

EC50 (95% C.I.) = 26 (23-30) mg a.i./L (mm) 

Probit slope (95% C.I.) = 9.1 (5.4-12.8) NOAEC = 4.8 mg a.i./L (mm) LAOEC = 7.9 mg a.i./L (mm) (NOAEC based on mortality and concentration dependent lethargy at ≥7.9 mg/L) 
89 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) Slightly toxic 

Freshwater invertebrate life cycle: 21 days, static renewal 

S-Metolachlor (Not reported) 

Water flea (Daphnia magna) 

NOAEC = 0.1 mg/L LOAEC = 0.5 mg/L (based on number of young per female) 

Freshwater invertebrate life cycle: 21 days, flow through (chronic) 

S-Metolachlor (98.9) 

Water flea(Daphnia magna) 

NOAEC = 5.17 mg a.i./L (mm) LOAEC = 10.0 mg a.i./L (mm) (NOAEC based most sensitive endpoints of length and dry weight; parental and offspring survival also affected) 

Estuarine/marine invertebrate acute 

S-Metolachlor Estuarine/marine 

species 

No data 

Estuarine/marine mollusc acute 

S-Metolachlor Estuarine/marine 

species 

No data 

Estuarine/marine invertebrate life cycle: 28 days, flow through (chronic) 

S-Metolachlor technical 

Mysid shrimp (Mysidopsis bahia) 

NOAEC = 0.130 mg a.i./L (mm) LOAEC = 0.250 mg a.i./L (mm) (based on most sensitive endpoints of female length and dry weight; reproduction also affected) 

Benthic freshwater invertebrate 

Metolachlor Freshwater species No data 

Benthic estuarine/marine invertebrate 

Metolachlor Estuarine/marine 

species 

No data 

Aquatic vascular plant: 14 days, static 

S-Metolachlor (97.6) 

Duckweed (Lemna gibba)

EC50 (95% C.I.) = 0.021 (0.019-0.023) mg a.i./L (mm) 

NOAEC = 0.0076 mg a.i./L (mm) LOAEC = 0.018 mg a.i./L (mm) (based on most sensitive endpoint of frond number, biomass affected; sublethal effects: less root formation at ≥0.0076 mg

compared to the control; chlorosis at ≥0.018 mg/L) 

Aquatic nonvascular plant: 120 hours, static 

S-Metolachlor (97.6) 

Green alga (Selenastrum capricornutum) 

EC50 (95% C.I.) = 0.0080 (0.0026-0.025) mg a.i./L (mm) 

NOAEC = 0.0015 mg a.i./L (mm) LOAEC = 0.0030 mg a.i./L (mm) (based on cell density; sublethal effects: bloated cells at ≥0.0mg/L; cell fragments at ≥0.0030 mg/L) 
90 

Study Type Test Substance 

 (% a.i.) 

Species Toxicity Endpoints and 

Acute Toxicity Classification (If Applicable) 

Aquatic nonvascular plant: 120 hours, static 

S-Metolachlor (97.6) 

Marine diatom (Skeletonema costatum) 

EC50 (95% C.I.) = 0.11 (0.091-0.128) mg a.i./L (mm) 

NOAEC = 0.021 mg a.i./L (mm) LOAEC = 0.081 mg a.i./L (mm) (based on cell density; sublethal effects: bloated cells at ≥0.0mg/L; cell fragments at ≥0.081 mg/L) 

Aquatic nonvascular plant: 96 hours, static 

S-Metolachlor (98.9) 

Freshwater diatom (Navicula pelliculosa) 

EC50 (95% C.I.) = 18 (17-20) mg a.i./L (TWA) 

NOAEC = 4.08 mg a.i./L (TWA) LOAEC = 9.9 mg a.i./L (TWA) (based on most sensitive endpoint of area under the growth curve; cell density and growth rate also affected) 

Aquatic nonvascular plant: 96 hours, static 

S-Metolachlor (98.9) 

Cyanobacterium (Anabaena flos-aquae) 

EC50 (95% C.I.) = 21 (19-23) mg a.i./L (mm) 

NOAEC = 9.6 mg a.i./L (mm) LOAEC = 19 mg a.i./L (mm) (based on most sensitive endpoint of cell density; area under growth curve (biomass and growth rate also affected) 

Abbreviations: C.I. = confidence interval; form. = formulation; im = initial measured; mm = mean measured; nom = nominal; NA = nospecified; TEP = typical end-use product; TWA = time-weighted average 
91 

Appendix E: SIP and STIR Outputs 

SIP (v. 1.0) 

Table 1. Inputs 

Parameter Value 

Chemical name metolachlor/S-metolachlor 

Solubility (in water at 25oC; mg/L) 480 

 

Mammalian LD50 (mg/kg-bw) 2780 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian species 

 

Mammalian NOAEL (mg/kg-bw) 15 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian species 

 

Avian LD50 (mg/kg-bw) 4640 

Avian test species mallard duck 

Body weight (g) of "other" avian species 

Mineau scaling factor 1.15 

 

Mallard NOAEC (mg/kg-diet) 800 

Bobwhite quail NOAEC (mg/kg-diet) 403 

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

Body weight (g) of other avian species 

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

Body weight (g) of 2nd other avian species 

 

Table 2. Mammalian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 82.5600 82.5600 

Adjusted toxicity value (mg/kg-bw) 2138.2664 11.5374 

Ratio of exposure to toxicity 0.0386 7.1559 

Conclusion* 

Drinking water exposure 

alone is NOT a potential 

concern for mammals 

Exposure through 

drinking water alone is 

a potential concern for 

mammals 

 

Table 3. Avian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 388.8000 388.8000 

Adjusted toxicity value (mg/kg-bw) 2409.2059 39.6901 

Ratio of exposure to acute toxicity 0.1614 9.7959 

Conclusion* Exposure through 

drinking water alone is a 

Exposure through 

drinking water alone is 
92 

potential concern for 

birds 

a potential concern for 

birds 

 

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

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

drinking water may contribute to a total exposure that has potential for effects to non-target animals. 

STIR (v. 1.0) 

Welcome to the EFED 

Screening Tool for Inhalation Risk 

This tool is designed to provide the risk assessor with a rapid method for determining 

the potential 

significance of the inhalation exposure route to birds and mammals in a risk 

assessment. 

 

Input 

Application and Chemical Information 

Enter Chemical Name 

metolachlor/Smetolachlor 

Enter Chemical Use Soybean and corn 

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

If Spray What Type (enter ground or air) ground 

Enter Chemical Molecular Weight (g/mole) 283.8 

Enter Chemical Vapor Pressure (mmHg) 2.85E-05 

Enter Application Rate (lb a.i./acre) 4 

 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 4640 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 1.58 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 2780 

Enter Lowest Rat Inhalation LC50 (mg/L) 1.75 

Duration of Rat Inhalation Study (hrs) 4 

Enter Rat Weight (kg) 0.35 

 

Output 

Results Avian (0.020 kg ) 

Maximum Vapor Concentration in Air at 

Saturation (mg/m3) 4.35E-01 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 5.47E-02 

Adjusted Inhalation LD50 1.17E+01 
93 

Ratio of Vapor Dose to Adjusted Inhalation LD50 4.66E-03

Exposure not Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 4.23E-01 

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 3.60E-02

Exposure not Likely 

Significant 

 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at 

Saturation (mg/m3) 4.35E-01 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 6.88E-02 

Adjusted Inhalation LD50 1.04E+02 

Ratio of Vapor Dose to Adjusted Inhalation LD50 6.60E-04

Exposure not Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 5.31E-01 

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 5.10E-03

Exposure not Likely 

Significant 

Welcome to the EFED 

Screening Tool for Inhalation Risk 

This tool is designed to provide the risk assessor with a rapid method for determining 

the potential 

significance of the inhalation exposure route to birds and mammals in a risk 

assessment. 

 

Input 

Application and Chemical Information 

Enter Chemical Name 

metolachlor/Smetolachlor 

Enter Chemical Use Soybean and corn 

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

If Spray What Type (enter ground or air) air 

Enter Chemical Molecular Weight (g/mole) 283.8 

Enter Chemical Vapor Pressure (mmHg) 2.85E-05 

Enter Application Rate (lb a.i./acre) 4 

 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 4640 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 1.58 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 2780 

Enter Lowest Rat Inhalation LC50 (mg/L) 1.75 
94 

Duration of Rat Inhalation Study (hrs) 4 

Enter Rat Weight (kg) 0.35 

 

Output 

Results Avian (0.020 kg ) 

Maximum Vapor Concentration in Air at 

Saturation (mg/m3) 4.35E-01 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 5.47E-02 

Adjusted Inhalation LD50 1.17E+01 

Ratio of Vapor Dose to Adjusted Inhalation LD50 4.66E-03

Exposure not Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 3.84E-01 

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 3.27E-02

Exposure not Likely 

Significant 

 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at 

Saturation (mg/m3) 4.35E-01 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 6.88E-02 

Adjusted Inhalation LD50 1.04E+02 

Ratio of Vapor Dose to Adjusted Inhalation LD50 6.60E-04

Exposure not Likely 

Significant 

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 4.83E-01 

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 4.64E-03

Exposure not Likely 

Significant