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Alachlor (Ref: CP 50144 )
Last updated: 16/12/2020
(Also known as: alachlore; acetanilide; methachlor; metachlor; CDMA)

SUMMARY
Alachlor is a pre-emergence chloroacetanilide herbicide that is not approved for use in the EU. 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.
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
UK regulatory status
UK COPR regulatory status
Not approved
Date COPR inclusion expires
Expired
UK LERAP status
No UK approval for use
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
                 
Also used in
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 group
Chloroacetamide
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Selective, systemic action absorbed by germinating shoots. Inhibition of 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
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
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 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
Colourless/yellow crystals
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • Lasso
  • Alanex
  • Pillarzo
Example products using this active
  • Monsanto
  • Makhteshim-Agan
  • Pillar International
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 (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 / IPCS INCHEM (ChemID; IPCS INCHEM )
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 (click here )
5 = Verified data used for regulatory purposes
High
Bulk 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 internet resources
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 (click here )
5 = Verified data used for regulatory purposes
Low volatility
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
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 (click here )
5 = Verified data used for regulatory purposes
Non-persistent
DT₅₀ (lab at 20 °C)
35
Q2 Q = Miscellaneous internet resources
2 = Unverified data of unknown source
Moderately persistent
DT₅₀ (field)
14
B4 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (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 on plant matrix
Value
- - -
Note
-
Dissipation rate RL₅₀ 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
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 (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 (click here )
4 = Verified data
Fast
Water phase only DT₅₀ (days)
- - -
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
R3 R = Peer reviewed scientific publications
3 = Unverified data of known source
Moderately mobile
Koc
335
Notes and range
-
Freundlich
Kf
16.5
R4 R = Peer reviewed scientific publications
4 = Verified data
Slightly mobile
Kfoc
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 -
Key metabolites
Metabolite
Formation medium
Estimated maximum occurrence fraction
1107/2009 relevancy
alachlor ethane sulphonate
Soil - -
alachlor oxanilic acid
Soil - -
ECOTOXICOLOGY
Property
Value
Source; quality score; and other information
Interpretation
Bio-concentration factor
BCF (l kg⁻¹)
39
P4 P = Other governments and regulators
4 = Verified data
Low potential
CT₅₀ (days)
Not available -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
930
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (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 (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 (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)
- - -
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
1.8
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Oncorhynchus mykiss
Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)
0.19
P3 P = Other governments and regulators
3 = Unverified data of known source
Unknown species
Moderate
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 (US EPA Databases Related to Pesticide Risk Assessment )
4 = Verified data
Daphnia magna
Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
0.22
P3 P = Other governments and regulators
3 = Unverified data of known source
Unknown species
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 - 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 (US EPA Databases Related to Pesticide Risk Assessment )
3 = Unverified data of known source
Lemna minor
Moderate
Non-target plants
- - -
- - -
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 (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
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
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)
- - -
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)
386.8
B5 B = UK CRD and ACP evaluation documents / and other Defra (UK) documents (click here )
5 = Verified data used for regulatory purposes
Moderate
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
- - -
Other soil macro-organisms
Acute LC₅₀ (mg kg⁻¹)
- - -
Chronic NOEC (mg kg⁻¹)
- - -
Other arthropod (1)
LR₅₀ g ha⁻¹
- - -
% Effect
- - -
Other arthropod (2)
LR₅₀ g ha⁻¹
- - -
% Effect
- - -
Soil micro-organisms
- - -
Mesocosm study data
NOEAEC mg l⁻¹
- - -
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)
930
F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (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)
0.01
L3 L = Pesticide manuals and hard copy reference books / other sources
3 = Unverified data of known source
-
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 
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 (click here )
5 = Verified data used for regulatory purposes
UK EA QS database 2018
-
Drinking Water MAC (μg l⁻¹)
- - -
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
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
CLP classification 2013
Health: H302, H317, H351
Environment: H400, H410
EC Risk Classification
Carcinogen category 3: R40
Xn - Harmful: R22, R43
N - Dangerous for the environment: R50, R53
EC Safety Classification
S2, S36/37, S46, S61, S60
WHO Classification
II (Moderately hazardous)
UN Number
2588
Waste disposal & packaging
-
TRANSLATIONS
Language
Name
English
alachlor
French
alachlore
German
Alachlor
Danish
alachlor
Italian
alaclor
Spanish
alacloro
Greek
-
Polish
alachlor
Swedish
-
Hungarian
alachlor
Dutch
alachloor

Record last updated: 16/12/2020
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