Dimethenamid-P

Dimethenamid-P	Last updated: 16/01/2023
(Also known as: dimethenamide-P; (S)-dimethenamid)

SUMMARY

Dimethanamid-P is a soil-applied herbicide. It is highly soluble in water and has a low volatility. It is not expected to be persistent in soil systems but may be persistent in water depending on local conditions. It is moderately toxic to birds, fish, aquatic invertebrates and algae but more so to aquatic plants. It is also moderately toxic to earthworms whilst its honeybee toxicity is low. Dimethenamid-P is also moderately toxic to mammals if ingested and is a skin and eye irritant, and skin sensitizer.

Data alerts

The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement.

Environmental fate	Ecotoxicity	Human health
Environmental fate Moderate alert: GUS: Transition state; Drainflow: Moderately mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate; Mammals chronic toxicity: Moderate; Possible Carcinogen; Possible Reproduction/development effects

GENERAL INFORMATION

Description

A pre-emergence herbicide often used to control annual grasses, annual broad-leaved weeds and sedges

Example pests controlled

Black grass; Chickweed; Cleavers; Mayweed; Forget-me-not; Speedwell; Shepherd's purse; Cranes-bill

Example applications

Soybeans; Vegetables including beans, onions, cabbage; Peanuts; Grapevines; Ornamentals; Sugarbeet; Sunflowers; Stone fruit

Efficacy & activity

Availability status

Current

Introduction & key dates

1999, USA; 2000, UK

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/08/2034

UK LERAP status

Possible - check label

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Germany/Bulgaria

Date EC 1107/2009 inclusion expires

31/08/2034

EU Candidate for substitution (CfS)

Listed in EU database

Yes

Approved for use (✓) under EC 1107/2009 in the following EU Member States

ATAustria	BEBelgium	BGBulgaria	CYCyprus	CZCzech Republic	DEGermany	DKDenmark	EEEstonia	ELGreece
✓	✓	✓	✓	✓	✓		✓	✓
ESSpain	FIFinland	FRFrance	HRCroatia	HUHungary	IEIreland	ITItaly	LTLithuania	LULuxembourg
✓	✓	✓	✓	✓	✓	✓	✓	✓
LVLatvia	MTMalta	NLNetherlands	PLPoland	PTPortugal	RORomania	SESweden	SISlovenia	SKSlovakia
✓		✓	✓	✓	✓	✓	✓	✓

Additional information

Also used in

Australia

Chemical structure

Isomerism

Dimethenamid-P is the more biologically active isomer of chiral dimethenamid and is used at lower rates.

Chemical formula

C₁₂H₁₈ClNO₂S

Canonical SMILES

CC1=CSC(=C1N(C(C)COC)C(=O)CCl)C

Isomeric SMILES

CC1=CSC(=C1N([C@@H](C)COC)C(=O)CCl)C

International Chemical Identifier key (InChIKey)

JLYFCTQDENRSOL-VIFPVBQESA-N

International Chemical Identifier (InChI)

InChI=1S/C12H18ClNO2S/c1-8-7-17-10(3)12(8)14(11(15)5-13)9(2)6-16-4/h7,9H,5-6H2,1-4H3/t9-/m0/s1

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide

Substance groups

Chloroacetamide herbicide; Amide herbicide

Minimum active substance purity

930 g kg⁻¹

Known relevant impurities

EU dossier - 1,1,1,2-tetrachloroethane <1.0 g kg⁻¹; 2,4-dimethylthiopene-3-ol <=1.5 g kg⁻¹

Substance origin

Synthetic

Mode of action

Selective, fatty acid inhibitor

CAS RN

163515-14-8

EC number

605-329-9

CIPAC number

638

US EPA chemical code

129501

PubChem CID

13633097

CLP index number

616-215-00-3

Molecular mass

275.8

PIN (Preferred Identification Name)

2-chloro-N-(2,4-dimethylthiophen-3-yl)-N-[(2S)-1-methoxypropan-2-yl]acetamide

IUPAC name

(S)-2-chloro-N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)acetamide

CAS name

2-chloro-N-(2,4-dimethyl-3-thienyl)-N-[(1S)-2-methoxy-1-methylethyl]acetamide

Other status information

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Herbicide Resistance Classification (WSSA)

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not applicable

Examples of recorded resistance

Physical state

Yellow-brown viscous liquid

Related substances & organisms

dimethenamid

Formulations

Property

Value

Example manufacturers & suppliers of products using this active now or historically

BASF

Example products using this active

Elk
Shadow
Springbok
Frontier X-2

Formulation and application details

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

1499

High

Solubility - In organic solvents at 20 °C (mg l⁻¹)

310000

n-Hexane

310000

n-Heptane

1000000

Toluene

1000000

Acetone

Melting point (°C)

Solidification below -50

Boiling point (°C)

280

Degradation point (°C)

101

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

7.76 X 10⁰¹

Calculated

Log P

1.89

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.2

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

2.51

Low volatility

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

4.80 X 10^-04

Non-volatile

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

236nm = 7560

Surface tension (mN m⁻¹)

52.0

at 20 °C 0.1%w/w

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

12.1

Non-persistent

DT₅₀ (field)

15.8

Non-persistent

DT₉₀ (lab at 20 °C)

44.6

Moderately persistent

DT₉₀ (field)

70.1

DT₅₀ modelling endpoint

Note

EU dossier Lab studies DT₅₀ range 5-31 days (normalised), DT₉₀ range 26-104 days, field studies DT₅₀ range 10-20 days (normalised), DT₉₀ range 48-167 days (normalised)

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

13.7

Moderately fast

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Stable

Note

Stable pH 5 to pH 9 over 30 days, 25 °C

Water-sediment DT₅₀ (days)

Fast

Water phase only DT₅₀ (days)

Slow

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

K_oc

Notes and range

Freundlich

K_f

3.69

Moderately mobile

K_foc

227

¹/_n

1.0

Notes and range

EU dossier K_f range 1.23-13.5 mL g⁻¹, K_foc range 90-474 mL g⁻¹, ¹/_n range 0.92 -1.07, Soils=10

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.97

Calculated

Transition state

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

5.49 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

Bio-concentration factor

BCF (l kg⁻¹)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

2-((2,4-dimethyl-3-thienyl)-((1S)-2-methoxy-1-methyl-ethyl)amino)-2-oxo-acetic acid (Ref: M656PH023)

Major fraction

0.122

2-((2,4-dimethyl-3-thienyl)-((1S)-2-methoxy-1-methyl-ethyl)amino)-2-oxo-ethanesulfonic (Ref: M656PH027)

Major fraction

0.133

2-(2-((2,4-dimethyl-3-thienyl)-((1S)-2-methoxy-1-methyl-ethyl)amino)-2-oxo-ethylsulfinylacetic acid (Ref: M656PH031)

Major fraction

0.103

Known groundwater metabolites

Metabolite

EC SANCO/221/2000 relevancy

ADI (mg kg⁻¹ bodyweight day⁻¹)

WHO drinking water guidance value (μg L⁻¹)

2-(2-((2,4-dimethyl-3-thienyl)-((1S)-2-methoxy-1-methyl-ethyl)amino)-2-oxo-ethylsulfinylacetic acid (Ref: M656PH031)

Not relevant

2-[2-[(2,4-dimethyl-3-thienyl)-[(1S)-2-methoxy-1-methyl-ethyl]amino]-2-oxo-ethyl]sulfanylacetic acid (Ref: M656PH032)

Not relevant

2-[2-[(2,4-dimethyl-3-thienyl)-[(1S)-2-methoxy-1-methyl-ethyl]amino]-2-oxo-ethyl]sulfonyl acetic acid (Ref: M656PH051)

Not relevant

3-{(hydroxyacetyl)[(2S)-1-methoxypropan-2-yl]amino}-4-methylthiophene-2-carboxylic acid (Ref: M656PH043)

Not relevant

N-(2,4-dimethylthiophen-3-yl)-N-[(2S)-1-methoxypropan-2-yl]acetamide (Ref: M656PH003)

Not relevant

(2S)-2-[(2,4-dimethyl-3-thienyl)-(2-sulfoacetyl)amino]propanoic acid (Ref: M656PH054)

Not relevant

2-[(2,4-dimethyl-3-thienyl)amino]-2-oxo-ethanesulfonic acid (Ref: M656PH055)

Not relevant

3-[[(1S)-2-methoxy-1-methyl-ethyl]amino]-4-methyl-thiophene-2-carboxylic acid (Ref: M656PH062)

Not relevant

2-((2,4-dimethyl-3-thienyl)-((1S)-2-methoxy-1-methyl-ethyl)amino)-2-oxo-acetic acid (Ref: M656PH023)

Not relevant

3-[((1S)-2-methoxy-1-methyl-ethyl)-oxalo-amino]-acid (Ref: M656PH045)

Not relevant

(E)-3-[[(1S)-2-methoxy-1-methyl-ethyl]-oxalo-amino]-2-methyl-4-oxo-pent-2-enoic acid (Ref: M656PH049)

Not relevant

2-[(2,4-dimethyl-3-thienyl)-[(1S)-2-hydroxy-1-methyl-ethyl]amino]-2-oxo-acetic acid (Ref: M656PH050)

Not relevant

2-((2,4-dimethyl-3-thienyl)-((1S)-2-methoxy-1-methyl-ethyl)amino)-2-oxo-ethanesulfonic (Ref: M656PH027)

Not relevant

N-(2,4-dimethyl-3-thienyl)-N-[(1S)-2-methoxy-1-methyl-ethyl]-2-methylsulfonyl-acetamide (Ref: M656PH010)

Not relevant

(E)-3-[[(1S)-2-methoxy-1-methyl-ethyl]-(2-sulfoacetyl)amino]-2-methyl-4-oxo-pent-2-enoic acid (Ref: M656PH052)

Not relevant

2-[[4-(hydroxymethyl)-2-methylene-5-oxo-3-thienyl]-[(1S)-2-methoxy-1-methyl-ethyl]amino]-2-oxo-ethanesulfonic acid (Ref: M656PH053)

Not relevant

2-[[(1S)-2-methoxy-1-methyl-ethyl]-(4-methyl-2-methylene-5-oxo-3-thienyl)amino]-2-oxo-ethanesulfonic acid (Ref: M656PH059)

Not relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

3,4-dihydro-4-(2,4-dimethyl-3-thienyl)-5-methyl-2H-1,4-oxazin-3-one

4-(2,4-dimethyl-3-thienyl)-5-methyl-3-morpholinone

N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-2-(methylsulfonyl)acetamide

Rat

N-(2,4-dimethyl-3-thienyl)-2-hydroxy-N-(2-methoxy-1-methylethyl)acetamide

N-(2,4-dimethyl-3-thienyl)-N-(2-hydroxy-1-methylethyl)acetamide

N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-2-(methylsulfinyl)acetamide

Rat

N-(2,4-dimethyl-3-thienyl)-N-(2-hydroxy-1-methylethyl)-2-(methylsulfonyl)acetamide

Rat

4-(2,4-dimethyl-3-thienyl)-6-hydroxy-5-methyl-3-morpholinone

Rat

sulfoxide of 2-[N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)amino]-2-oxoethyl-N-malonyl cysteine

Rat

2-[N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)amino]-2-oxoethyl thioglycolic acid

Rat

sulfoxide of 2-[N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)amino]-2-oxoethyl thiolactic acid

Rat

N-(2-hydroxymethyl-4-methyl-3-thienyl)-N-(2-methoxy-1-methylethyl)-2-(methylsulfinyl)acetamide

Rat

N-acetyl-S-(2-(N'-(2,4-dimethyl-3-thienyl)-N'-(2-methoxy-1-methylethyl)amino)-2-oxoethyl)cysteine

mercapturate conj

Rat

methylated N-(2,4-dimethyl-3-thienyl-N-(2-methoxy-2-methylthio-acetyl)alanine

Rat

methylated N-(2,4-dimethyl-3-thienyl)-N-((methylsulfonyl)acetyl)alanine

Rat

1,5-dihydro-1-(2-methoxy-1-methylethyl)- 8-methylthieno-[thieno-[3,4-f][4,1]oxazepin-2(3H)-one

Rat

4-(2,4-dimethyl-3-thienyl)-6-hydroxy-5-methyl-3-thiomorpholinone

Rat

2,2'-dithiobis(N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)acetamide)

Rat

2-[N-(2,4-dimethyl-3-thienyl)-N- (2-methoxy-1-methylethyl)amino]-2-oxoethyl-glutathione

glutathione conj

Rat

2-[N-(2,4-dimethyl-3-thienyl)-N- (2-methoxy-1-methylethyl)amino]-2-oxoethyl-cysteine

Rat; Plant

2-[N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)amino]-2-oxoethyl-thiolactic acid

thiolactic acid conj

Rat; Plant

sulfoxide of 2-[N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)amino]-2-oxoethyl cysteine

Rat

N-(2,4-dimethyl-3-thienyl)-N-(2-hydroxy-1-methylethyl)-2-(methylsulfinyl)acetamide

Rat

N-(2,4-dimethyl-3-thienyl)-N-(2-methoxy-1-methylethyl)acetamide

dechlorinated dimethanamid

Sediment; Water

2-chloro-N-(2,4-dimethyl-3-thienyl)- N-(2-hydroxy-1-methylethyl)acetamide

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

429

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

150

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

1068

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 5620 ppm

Colinus virginianus

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

114

Colinius virginianus NOAEL

Moderate

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

294.4

Eisenia foetida

Moderate

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

25.4

Eisenia foetida

Moderate

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect

Dose: 4.93 kg ha⁻¹

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

12.5

Folsomia candida

Non-target plants

Honeybees (Apis spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 200

Apis mellifera

Low

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

118.4

Apis mellifera

Low

Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

Chronic

Bumblebees (Bombus spp.)

Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

200

Bombus terrestris 48hr

Low

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 158

Bombus terrestris 48hr

Low

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

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings) as Mortality LR₅₀ g ha⁻¹

> 1050

Chrysoperla carnea

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹

47.25

Aphidius rhopalosiphi

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹

> 1050

Typhlodromus pyri

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

2.6

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

2.5

Oncorhynchus mykiss

Moderate

Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

3.2

Daphnia magna

Moderate

Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

1.25

Daphnia magna

Moderate

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

2.7

Americamysis bahia

Moderate

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)

0.0060

Lemna gibba

High

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

0.019

Pseudokirchneriella subcapitata

Moderate

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

Mesocosm study data

NOEAEC mg l⁻¹

HUMAN HEALTH AND PROTECTION

General

Property

Value

Source; quality score; and other information

Interpretation

Threshold of Toxicological Concern (Cramer Class)

High (class III)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

429

Rat

Moderate

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.16

Rat 4 hr (head/nose only)

Other Mammal toxicity endpoints

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

0.02

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

0.25

Rat SF=100

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

0.1

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

No unacceptable risks to bystanders identified

Occupational

Acceptable for intended uses

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

General human health issues

Possible liver toxicant

Handling issues

Property

Value and interpretation

General

Prevent generation of mists
Not explosive or oxidising
Not expected to autoignite; Not highly flammable

CLP classification 2013

Health: H302, H317
Environment: H400

WHO Classification

NL (Not listed)

UN Number

Waste disposal & packaging

TRANSLATIONS

Language

Name

English

dimethenamid-P

French

dimethenamid-P

German

Dimethenamid-P

Danish

dimethenamid-P

Italian

dimetenamid-P

Spanish

dimetenamida-P

Greek

Polish

dimetenamid-P

Swedish

Hungarian

dimethenamid-P

Dutch

dimethenamide-P

Record last updated:	16/01/2023
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242