Alachlor (Ref: CP 50144 )	Last updated: 22/08/2024
(Also known as: alachlore; acetanilide; methachlor; metachlor; CDMA)

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SUMMARY

Alachlor is a pre-emergence chloroacetanilide herbicide. It is moderately soluble in water, quite volatile and is not expected to readily leach to groundwater. It tends not to persist in either soil or water systems. It has a moderate mammalian toxicity and a low potential for bioaccumulation. Alachlor is moderately toxic to birds, most aquatic organisms, honeybees and earthworms.

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: Drainflow: Moderately mobile; Potential for particle bound transport: Medium	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate; Possible Carcinogen; Endocrine disrupter; Reproduction/development effects

GENERAL INFORMATION

Description	A chloroacetanilide herbicide for pre-emergence control of annual grasses and broad-leaved weeds
Example pests controlled	Goosegrass; Crab grass; Herringbone grass; Sweet buffalo grass; Barnyard grass; Nutsedge; Pigweed; Sow thistle; Purslane; Chickweed
Example applications	Maize; Potatoes; Soybean; Sunflowers; Brassicas; Pineapples; Sugarcane
Efficacy & activity	-
Availability status	Current
Introduction & key dates	1969, first introduced

GB regulatory status

GB COPR regulatory status	Not approved
Date COPR inclusion expires	Expired
GB LERAP status	No UK approval for use as a pesticide

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status	Not approved
Dossier rapporteur/co-rapporteur	Spain
Date EC 1107/2009 inclusion expires	Expired
EU Candidate for substitution (CfS)	Not applicable
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
Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries	ISIceland NONorway

Additional information

Also used in	USA, Japan

Chemical structure

Isomerism	None
Chemical formula	C₁₄H₂₀ClNO₂
Canonical SMILES	CCC1=C(C(=CC=C1)CC)N(COC)C(=O)CCl
Isomeric SMILES	No data
International Chemical Identifier key (InChIKey)	XCSGPAVHZFQHGE-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C14H20ClNO2/c1-4-11-7-6-8-12(5-2)14(11)16(10-18-3)13(17)9-15/h6-8H,4-5,9-10H2,1-3H3
2D structure diagram/image available?	Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
alachlor	-

General status

Pesticide type	Herbicide
Substance groups	Chloroacetanilide herbicide
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Selective, systemic action absorbed by germinating shoots. Inhibition of very long chain fatty acids (VLCFA, inhibition of cell division)
CAS RN	15972-60-8
EC number	240-110-8
CIPAC number	204
US EPA chemical code	090501
PubChem CID	2078
CLP index number	616-015-00-6
Molecular mass	269.77
PIN (Preferred Identification Name)	2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide
IUPAC name	2-chloro-2',6'-diethyl-N-methoxymethylacetanilide
CAS name	2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide
Other status information	WFD priority substance; OSPAR candidate; Potential groundwater contaminant; Chemical subject to PIC regulations; PAN Bad Actor
Relevant Environmental Water Quality Standards	EU Directive 2008/105/EC EQS surface waters: annual average 0.3 µg l⁻¹; max measured 0.7 µg l⁻¹
Herbicide Resistance Class (HRAC MoA class)	K3
Herbicide Resistance Class (WSSA MoA class)	15
Insecticide Resistance Class (IRAC MoA class)	Not applicable
Fungicide Resistance Class (FRAC MOA class)	Not applicable
Examples of recorded resistance	-
Physical state	Colourless/yellow crystals

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Monsanto Makhteshim-Agan Pillar International
Example products using this active	Lasso Alanex Pillarzo Bullet Cannon Bronco
Formulation and application details	Usually supplied as emulsifiable concentrates, microscopic capsules and granules

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		240	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Moderate
Solubility - In organic solvents at 20 °C (mg l⁻¹)		-	-	-
Melting point (°C)		41	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Boiling point (°C)		100	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	-
Degradation point (°C)		105	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Flashpoint (°C)		137	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source (closed cup)	-
Octanol-water partition coefficient at pH 7, 20 °C	P	1.23 X 1003	Calculated	-
	Log P	3.09	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	High
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		1.13	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		0.62	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-
		Strong acid
Vapour pressure at 20 °C (mPa)		2.9	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Low volatility. If applied directly to plants or soil, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		3.20 X 10-03	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Non-volatile
Volatilisation as max % of applied dose lost	From plant surface	-	-	-
	From soil surface	-	-	-
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		-	-	-
Surface tension (mN m⁻¹)		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
General biodegradability		-
Soil degradation (days) (aerobic)	DT₅₀ (typical)	14	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Non-persistent
	DT₅₀ (lab at 20 °C)	35	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source	Moderately persistent
	DT₅₀ (field)	14	B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 4 = Verified data	Non-persistent
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	Field studies DT₅₀ range 1-3 weeks; Other sources: DT₅₀ 80 days (R2)
Dissipation rate RL₅₀ (days) on plant matrix	Value	-	-	-
	Note	-
Dissipation rate RL₅₀ (days) on and in plant matrix	Value	-	-	-
	Note	-
Aqueous photolysis DT₅₀ (days) at pH 7	Value	0.5	K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source	Fast
	Note	Stable to UV light
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	0.5	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Non-persistent
	Note	-
Water-sediment DT₅₀ (days)		2	B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 4 = Verified data	Fast
Water phase only DT₅₀ (days)		-	-	-
Sediment phase only DT₅₀ (days)		-	-	-
Air degradation		As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.
Decay in stored produce DT₅₀		-

Soil adsorption and mobility

Property		Value	Source; quality score; and other information	Interpretation
Linear	Kd (mL g⁻¹)	-	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source	Moderately mobile
	Koc (mL g⁻¹)	335
	Notes and range	-
Freundlich	Kf (mL g⁻¹)	16.5	R4 R = Peer reviewed scientific publications 4 = Verified data	Slightly mobile
	Kfoc (mL g⁻¹)	1994
	1/n	0.81
	Notes and range	Literature values: Kf range 11.8-20.5 mL g⁻¹; Kfoc range 339-4214 mL g⁻¹, 1/n range 0.70-0.91, Soils = 5
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		0.80	Calculated	Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	1.31 X 10-02	Calculated	-
	Note	-
Potential for particle bound transport index		Medium	Calculated	-
Potential for loss via drain flow		Moderately mobile	Calculated	-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk		-	-	-
Bio-concentration factor	BCF (l kg⁻¹)	39	P4 P = Other non-EU, UK or US Governments and Regulators 4 = Verified data	Low potential
	CT₅₀ (days)	Not available		-

Known soil metabolites

Metabolite	Major/Minor fraction	Estimated maximum occurrence fraction	Notes
alachlor ethane sulphonate	-	-	-
alachlor oxanilic acid	-	-	-

Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		930	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Rat	Moderate
Mammals - Short term dietary NOEL	(mg kg⁻¹)	10	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes Rat	High
	(ppm diet)	200		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		1536	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes Colinus virginianus	Moderate
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		386.8	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Moderate
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)		-	-	-
Soil micro-organisms		-	-	-
Collembola	Acute LC₅₀ (mg kg⁻¹)	-	-	-
	Chronic NOEC (mg kg⁻¹)	-	-	-
Non-target plants		-	-	-
		-	-	-
Honeybees (Apis spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	16	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	Moderate
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	Chronic	-	-	-
	Notes	-
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 bee species (1)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	-	-	-
	Mode of exposure	-
Other bee species (2)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	-	-	-
	Mode of exposure	-
Beneficial insects (Ladybirds)		-	-	-
Beneficial insects (Lacewings)		-	-	-
Beneficial insects (Parasitic wasps)		-	-	-
Beneficial insects (Predatory mites)		-	-	-
Beneficial insects (Ground beetles)		-	-	-

Aquatic ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		1.8	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes Oncorhynchus mykiss	Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)		0.19	P3 P = Other non-EU, UK or US Governments and Regulators 3 = Unverified data of known source Unknown species	Moderate
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		> 0.8	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Danio rerio	Moderate
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		10	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Daphnia magna	Moderate
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		0.22	P3 P = Other non-EU, UK or US Governments and Regulators 3 = Unverified data of known source Unknown species	Moderate
Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		7.9	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Ceriodaphnia dubia LC₅₀	Moderate
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
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 (free-floating, growth) - Acute 7 day EC₅₀, biomass (mg l⁻¹)		0.01	F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 3 = Unverified data of known source Lemna minor	Moderate
Aquatic plants (rooted, growth) - Acute 14 day EC₅₀, biomass (mg l⁻¹)		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		0.966	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Scenedesmus quadricauda	Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		0.02	J3 J = Pesticide Action Network database (click here ) 3 = Unverified data of known source Chlorella pyrenoidosa	Moderate
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	NOEAEC mg l⁻¹	-	-	-
Marine bivalves		-	-	-

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)		930	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Rat	Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		13300	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rabbit	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		1.04	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
Other Mammal toxicity endpoints		-	-	-
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)		-	-	-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)		-	-	-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)		-	-	-
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)		-	-	-
Dermal penetration studies (%)		-	-	-
Dangerous Substances Directive 76/464		-	-	-
Exposure Routes	Public	Low risk to Europeans as no longer approved for use
	Occupational	Occupational exposure may occur through inhalation and dermal contact
MRLs	European	EU MRL pesticide database
	Great Britain	GB MRL Register
	Notes	-
Drinking Water Standards		Non-statutory WHO drinking water guideline 0.02 mg l⁻¹	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes UK EA QS database 2018	-
Drinking Water MAC (μg l⁻¹)		-	-	-
Mammalian dose elimination route and rate		-	-	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor ?Possibly, status not identified A3 A = Chromosome aberration (EFSA database) 3 = Negative ; B0 B = DNA damage/repair (EFSA database) 0 = No data ; C0 C = Gene mutation (EFSA database) 0 = No data ; D0 D = Genome mutation (EFSA database) 0 = No data ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative ?Possibly, status not identified Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant ?Possibly, status not identified XNo, known not to cause a problem XNo, known not to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser XNo, known not to cause a problem ?Possibly, status not identified ?Possibly, status not identified Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		US Toxics Release Inventory (TRI) Program listed carcinogen; CLP data - suspected carcinogen; US EPA - likely to be a human carcinogen at high doses Probable lung and kidney toxicant Causes irreversible eye damage Possibly genotoxic Endocrine issues - Competitive binding to estrogen and progesterone receptors

Handling issues

Property	Value and interpretation
General	Corrosive IMDG Transport Hazard Class 9
CLP classification 2013	Health: H302, H317, H351 Environment: H400, H410
WHO Classification	II (Moderately hazardous)
UN Number	UN3077
Waste disposal & packaging	Packaging Group III (minor danger)
Shelf-life, storage, stability and reactivity	Chemically stable under standard ambient conditions

TRANSLATIONS

Language	Name
English	alachlor
French	alachlore
German	Alachlor
Danish	alachlor
Italian	alaclor
Spanish	alacloro
Greek	-
Polish	alachlor
Swedish	-
Hungarian	alachlor
Dutch	alachloor
Norwegian	-

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Record last updated:	22/08/2024
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