| S-metolachlor (Ref: CGA 77102) |
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GENERAL INFORMATION 
for S-metolachlor
Description: Isomer herbicide mixture used to control grasses and some broad-leaved weeds in a wide range of crops
Example pests controlled: Nightshade; Crabgrass; Pigweed; Foxtail; Yellow nutsedge; Witchgrass
Example applications: Corn; Soybeans; Beans & peas; Potatoes; Sugarbeet; Lupin; Sunflower; Fruit trees
Efficacy & activity: Efficacy demonstrated by extensive use and field trials
Availability status: Current
Introduction & key dates: circa 1998
EC Regulation 1107/2009 (repealing 91/414):
| Status | Approved |
| Dossier rapporteur/co-rapporteur | Germany/France |
| Date inclusion expires | 31/07/2020 |
| EU Candidate for substitution (CfS) | No |
| Listed in EU database | Yes |
Approved for use (
) or known to be used (
) in the following European countries: 
AT |
BE |
BG |
CY |
CZ |
DE |
DK |
EE |
EL |
ES |
FI |
FR |
HR |
HU |
IE |
IT |
LT |
LU |
LV |
MT |
NL |
PL |
PT |
RO |
SE |
SI |
SK |
UK |
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Also used in: Australia
Chemical structure:
| Isomerism | Metolachlor exisits as the S- and R- entantiomers. S-metolachlor is a mixture of the S- and R-formats in an approximate ratio 88:12 . |
| Chemical formula | C15H22ClNO2 |
| Canonical SMILES | C1=CC(=CC=C1CSC(=NC2=C(C=C(C=C2)Cl)Cl)CN3C=NC=N3)Cl |
| Isomeric SMILES | No data |
| International Chemical Identifier key (InChIKey) | WVQBLGZPHOPPFO-LBPRGKRZSA-N |
| International Chemical Identifier (InChI) | InChI=1S/C15H22ClNO2/c1-5-13-8-6-7-11(2)15(13)17(14(18)9-16)12(3)10-19-4/h6-8,12H,5,9-10H2,1-4H3/t12-/m0/s1 |
| 2D structure diagram/image available? | Yes |
General status:
| Pesticide type | Herbicide | |
| Substance group | Chloroacetamide | |
| Minimum active substance purity | 960 g/kg | |
| Known relevant impurities | EU dossier - None declared | |
| Substance origin | Synthetic | |
| Mode of action | Selective, absorbed through roots and shoots. Inhibition of VLCFA (inhibition of cell division). | |
| CAS RN | 87392-12-9 | |
| Alternative/old CAS RN | 178961-20-1 | |
| EC number | 257-060-8 | |
| CIPAC number | 607 | |
| US EPA chemical code | 108800 | |
| PubChem CID | 11140605 | |
| Molecular mass (g mol-1) | 283.79 | |
| PIN (Preferred Identification Name) | mixture of 80–100% 2-chloro-N-(2-ethyl-6-methylphenyl)-N-[(2S)-1-methoxypropan-2-yl]acetamide and 20–0% 2-chloro-N-(2-ethyl-6-methylphenyl)-N-[(2R)-1-methoxypropan-2-yl]acetamide | |
| IUPAC name | mix of: (aRS,1S)-2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)acet-o-toluidide and 20–0% (aRS,1R)-2-chloro-6'-ethyl-N-(2-methoxy-1-methylethyl)acet-o-toluidide | |
| CAS name | 2-chloro-N-(2-ethyl-6-methylphenyl)-N-((1S)-2-methoxy-1-methylethyl)acetamide | |
| Other status information | Possible groundwater contaminant | |
| Relevant Environmental Water Quality Standards | - | |
| Herbicide Resistance Classification (HRAC) | K3 | |
| Herbicide Resistance Classification (WSSA) | 15 | |
| Insecticide Resistance Classification (IRAC) | Not applicable | |
| Fungicide Resistance Classification (FRAC) | Not applicable | |
| Examples of recorded resistance | - | |
| Physical state | Clear straw-coloured liquid | |
| Related substances & organisms | ||
Formulations:
| Property |
Value | |||
| Example manufacturers & suppliers of products using this active now or historically |
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| Example products using this active |
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| UK LERAP status | No UK approval for use as a pesticide under EC Regulation 1107/2009 | |||
| Formulation and application details | Usually supplied as emulsifiable concentrates. | |||
ENVIRONMENTAL FATE
for S-metolachlor
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Solubility - In water at 20oC (mg l-1) | 480 | A5 - @ 25 DegC | Moderate | |
| Solubility - In organic solvents at 20oC (mg l-1) | Miscible | A5 - Acetone | - | |
| Miscible | A5 - Methanol | - | ||
| Miscible | A5 - Toluene | - | ||
| Miscible | A5 - n-Hexane | - | ||
| Melting point (oC) | -61.1 | A5 | - | |
| Boiling point (oC) | 334 | A5 | - | |
| Degradation point (oC) | 290 | A5 | - | |
| Flashpoint (oC) | Not expected to self ignite; Not highly flammable | A5 | - | |
| Octanol-water partition coefficient at pH 7, 20oC | P | 1.12 X 1003 | Calculated | - |
| Log P | 3.05 | A5 - @ 25 DegC | High | |
| Bulk density (g ml-1)/Specific gravity | 1.12 | A5 | - | |
| Dissociation constant (pKa) at 25oC | Not applicable | A5 | - | |
| Note: No dissociation | ||||
| Vapour pressure at 20oC (mPa) | 3.7 | A5 | Low volatility | |
| Henry's law constant at 25oC (Pa m3 mol-1) | 2.20 X 10-03 | A5 | Non-volatile | |
GUS leaching potential index  |
2.32 | Calculated | Transition state | |
| SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate |
Value | 1.01 X 10-01 | Calculated | - |
| Note | - | |||
| Potential for particle bound transport index |
- | Calculated | Medium | |
| Maximum UV-vis absorption L mol-1 cm-1 | 266nm = 534; [274nm = 443; [>=290nm = 10 | A5 | - | |
| Surface tension (mN m-1) | - | - | - | |
Degradation:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
General biodegradability | - |
| Soil degradation (days) (aerobic) | DT50 (typical) | 51.8 | A5 | Moderately persistent |
| DT50 (lab at 20oC) | 51.8 | A5 | Moderately persistent | |
| DT50 (field) | 23.17 | A5 | Non-persistent | |
| DT90 (lab at 20oC) | - | - | - | |
| DT90 (field) | 111.8 | A5 | - | |
| DT50 modelling endpoint | - | - | - | |
| Note | EFSA 2018 lab studies DT50 (normalised) range 10.3-221 days, Soils=21. Field studies DT50 (measured) range 3.55-55.7 days, DT90 (measured) range 27.6-256 days, Soils=17. EU 2003 dossier lab studies DT50 range 7.6-37.6 days, DT90 range 25.1-125 days; field studies DT50 range 11-31 days, 6 soils, Europe, DT90 range 36-148 days | |||
| Dissipation rate RL50 on plant matrix | Value | - | - | - |
| Note | - | |||
| Dissipation rate RL50 on and in plant matrix | Value | 11.6 | R4 | - |
| Note | Published literature RL50 range 5.8-20.3 days, 3 field grown crops, various matrices, n=4 | |||
| Aqueous photolysis DT50 (days) at pH 7 | Value | 146 | A5 | Stable |
| Note | Limited photolysis occurs | |||
| Aqueous hydrolysis DT50 (days) at 20oC and pH 7 | Value | Stable | A5 | - |
| Note | Stable pH 5 to 9 at 25 DegC | |||
| Water-sediment DT50 (days) | 43.3 | A5 | Moderately fast | |
| Water phase only DT50 (days) | 9 | A5 | Moderately fast | |
Soil adsorption and mobility:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Linear | Kd | - | - | - |
| Koc | - | |||
| Notes and range | - | |||
| Freundlich | Kf | 3.63 | A5 | Moderately mobile |
| Kfoc | 200.2 | |||
| 1/n | 0.93 | |||
| Notes and range | EU 2018 dossier Kf range 1.0-44.8 mL/g, Kfoc range 112-368 mL/g, 1/n range 0.887-1.002, Soils=12 | |||
| pH sensitivity | No | |||
Key metabolites:
| Metabolite | Formation medium | Estimated maximum occurrence fraction | 1107/2009 relevancy |
|
| metolachlor oxanilic acid (Ref: CGA 51202) |
Soil | 0.211 | Major fraction, Relevant | |
| metolachlor ethane sulfonic acid (Ref: CGA 354743) |
Soil | 0.213 | Major fraction, Relevant | |
| 2-((2-Ethyl-6-methyl-phenyl)-oxalylamino)-propionic acid (Ref: CGA 357704) |
Soil | 0.219 | Major fraction, Relevant | |
ECOTOXICOLOGY
for S-metolachlor
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Bio-concentration factor | BCF (l kg-1) | 68.8 | A5 Whole fish | Low potential |
| CT50 (days) | 1.5 | - | ||
| Mammals - Acute oral LD50 (mg kg-1) | > 2000 | A5 Rat | Low | |
| Mammals - Short term dietary NOEL | (mg kg-1) | 15 | A5 Dog | High |
| (ppm diet) | - | - | ||
| Birds - Acute LD50 (mg kg-1) | >= 2510 | A5 Anas platyrhynchos | Low | |
| Birds - Short term dietary (LC50/LD50) | - | - | - | |
| Fish - Acute 96 hour LC50 (mg l-1) | 1.23 | A5 Oncorhynchus mykiss | Moderate | |
| Fish - Chronic 21 day NOEC (mg l-1) | 0.78 | A5 Pimephales promelas, 35 day | Moderate | |
| Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) | 11.2 | A5 Daphnia magna | Moderate | |
| Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) | 5.2 | A5 Daphnia magna | Moderate | |
| Aquatic crustaceans - Acute 96 hour LC50 (mg l-1) | 1.4 | A5 Mysidopsis bahia | Moderate | |
| Sediment dwelling organisms - Acute 96 hour LC50 (mg l-1) | - | - | - | |
| Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l-1) | 8.0 | A5 Chironomus riparius | Moderate | |
| Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg-1) | > 160 | A5 Chironomus riparius | Low | |
| Aquatic plants - Acute 7 day EC50, biomass (mg l-1) | 0.037 | A5 Lemna gibba, 14d | Moderate | |
| Non-target plants | - | - | - | |
| - | - | - | ||
| Algae - Acute 72 hour EC50, growth (mg l-1) | 0.017 | A5 Pseudokirchneriella subcapitata | Moderate | |
| Algae - Chronic 96 hour NOEC, growth (mg l-1) | 0.012 | A4 Pseudokirchneriella subcapitata, 72hr | Moderate | |
| Honeybees (Apis spp.) | Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | > 200 | A5 Apis mellifera | Low |
| Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | > 85 | A5 Apis mellifera | Moderate | |
| Unknown mode acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | - | - | - | |
| Bumblebees (Bombus spp.) | Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | - | - | - |
| - | ||||
| Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | - | - | - | |
| - | ||||
| Mason bees (Osmia spp.) | Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | - | - | - |
| Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | - | - | - | |
| Other pollinators (1) | Acute LD50 (worst case from 24 , 48 and 72 hour values - μg insect-1) | - | - | - |
| Mode of exposure | - | |||
| Other pollinators (2) | Acute LD50 (worst case from 24 , 48 and 72 hour values - μg insect-1) | - | - | - |
| Mode of exposure | - | |||
| Earthworms - Acute 14 day LC50 (mg kg-1) | 570 | A5 | Moderate | |
| Earthworms - Chronic NOEC, reproduction (mg kg-1) | < 26.65 | A5 Eisenia andrei, corr | Moderate | |
| Other soil macro-organisms | Acute LC50 (mg kg-1) | - | - | - | Chronic NOEC (mg kg-1) | - | - | - |
| Other arthropod (1) | LR50 g ha-1 | 1.6 | > A5 Typhlodromus pyri |
- |
| % Effect | 30.1 | Beneficial capacity A5 Typhlodromus pyri |
- | |
| Other arthropod (2) | LR50 g ha-1 | 1.6 | > A5 Aphidius rhopalosiphi |
- |
| % Effect | 25.4 | Beneficial capacity A5 Aphidius rhopalosiphi |
- | |
| Soil micro-organisms | Nitrogen mineralisation: No significant adverse effect Carbon mineralisation: No significant adverse effect |
A5 Dose = 12.67 kg ha-1 |
- | |
| Mesocosm study data | NOEAEC mg l-1 | - | - | - |
| NOEAEC mg l-1 | - | - | - | |
HUMAN HEALTH AND PROTECTION
for S-metolachlor
General:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Threshold of Toxicological Concern (Cramer Class) |
High (class III) | - | - | |
| Mammals - Acute oral LD50 (mg kg-1) | > 2000 | A5 Rat | Low | |
| Mammals - Dermal LD50 (mg kg-1 body weight) | > 2000 | A5 Rat | - | |
| Mammals - Inhalation LC50 (mg l-1) | > 2.91 | A5 Rat 4hr (nose only) | - | |
| Other Mammal toxicity endpoints | - | - | ||
| ADI - Acceptable Daily Intake (mg kg-1bw day-1) | 0.1 | A5 Dog, SF=100 | - | |
| ARfD - Acute Reference Dose (mg kg-1bw day-1) | 0.5 | A5 Rat, SF=100 | - | |
| AAOEL - Acute Acceptable Operator Exposure Level (mg kg-1 bw day-1) | None allocated | A5 | - | |
| AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) | 0.1 | A5 Dog, SF=100 | - | |
| Dermal penetration studies (%) | 0.4-13% | A5 concentration dependent | - | |
| Dangerous Substances Directive 76/464 | - | - | - | |
| Exposure Routes | Public | Main risk for bystanders and residents arises from spray drift | ||
| Occupational | Acceptable levels with PPE/PPC | |||
| European MRLs | Click here for the EU MRL pesticide database | |||
| Drinking Water Standards | - | - | - | |
| Drinking Water MAC (μg l-1) | - | - | - | |
Health issues:
| Carcinogen | Genotoxic | Endocrine disrupter | Reproduction / development effects | Cholinesterase inhibitor | Neurotoxicant | |||
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A0; B0; C0; D0; E0 |
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| Respiratory tract irritant | Skin irritant | Skin sensitiser | Eye irritant | Phototoxicant | ||||
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| General human health issues | Possible liver and thyroid toxicant USEPA - possible human carcinogen |
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| Key: Genotoxicity A: Chromosome aberration (EFSA database) B: DNA damage/repair (EFSA database) C: Gene mutation (EFSA database) D: Genome mutation (EFSA database) E: Unspecified genotoxicity type (miscellaneous data source) 0: No data 1: Positive 2: Mixed/ambiguous results 3: Negative |
Key: Other : Yes, known to cause a problem  : No, known not to cause a problem  : Possibly, status not identified - : No data found |
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Handling issues:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
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| General |
Not explosive or oxidising | |||
| CLP classification 2013 | Health: H317 Environment: H400, H410 |
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| EC Risk Classification |
Xn - Harmful: R43 N - Dangerous for the environment: R50, R53 |
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| EC Safety Classification |
S2, S24, S37, S60, S61 | |||
| WHO Classification | III | - | Slightly hazardous | |
| UN Number | Usually 3077 | |||
| Waste disposal & packaging |
- | |||
TRANSLATIONS
for S-metolachlor
| Language | Name |
| English | S-metolachlor |
| French | S-metolachlore |
| German | S-Metolachlor |
| Danish | S-metolachlor |
| Italian | S-metolaclor |
| Spanish | S-metolachloro |
| Greek | S-metolachlor |
| Slovenian | S-metolaklor |
| Polish | S-metolachlor |
| Swedish | - |
| Hungarian | S-metolachlor |
| Dutch | S-metolachloor |
Record last updated: Wednesday 27 November 2019
Contact: aeru@herts.ac.uk