Butachlor is a herbicide used for pre-emergence control of annual grasses and some broad-leaved weeds. It has a low aqueous solubility and a low volatility. Depending on local conditions it may be moderately persistent in some soils. It is not expected to leach to groundwater. It is moderately toxic to most fauna and flora, the main exception being honeybees for which butachlor has a low toxicity. It has a moderate oral mammalian toxicity if ingested and is both a skin and eye irritant.
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: Slightly mobile
Ecotoxicity High alert: Earthworms acute ecotoxicity: High
Human health Moderate alert: Mammals acute toxicity: Moderate; Possible Carcinogen
Warning: Significant data are missing
GENERAL INFORMATION
Description
A herbicide used for pre-emergence control of annual grasses and some broad-leaved weeds particularly in rice crops
Example pests controlled
Barnyardgrass; Crab grass; Torpedo grass; Witchgrass; Red deadnettle
Example applications
Rice; Wheat; Barley; Peanuts
Efficacy & activity
-
Availability status
-
Introduction & key dates
circa 1970, introduced
UK regulatory status
UK COPR regulatory status
Not approved
Date COPR inclusion expires
Not applicable
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
Not applicable
Date EC 1107/2009 inclusion expires
Not applicable
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
Approved for use (✓) under EC 1107/2009 by Mutual Recognition of Authorisation and/or national regulations in the following EEA countries
Example manufacturers & suppliers of products using this active now or historically
Monsanto
FCC
King Tech Corp
Makhteshim-Agan
Pillar International
BOC Sciences
Example products using this active
Machete
Weedout
Butanox
Vendaval
Formulation and application details
Usually supplied as an emulsifiable concentrate or as granules.
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
20
H4 H = The US ARS pesticide properties database. Dataset is no longer available. 4 = Verified data
Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)
-
-
-
Melting point (°C)
-2.8
E4 E = Manufacturers safety data sheets 4 = Verified data
-
Boiling point (°C)
156
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Degradation point (°C)
165
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Flashpoint (°C)
-
-
-
Octanol-water partition coefficient at pH 7, 20 °C
P
3.16 X 1004
Calculated
-
Log P
4.5
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
High
Fat solubility of residues
Solubility
-
-
-
Data type
-
-
-
Density (g ml⁻¹)
1.073
E4 E = Manufacturers safety data sheets 4 = Verified data
-
Dissociation constant pKa) at 25 °C
-
-
-
-
Vapour pressure at 20 °C (mPa)
0.24
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low volatility. If applied directly to plants, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
3.74 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)
56
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Moderately persistent
DT₅₀ (lab at 20 °C)
-
-
-
DT₅₀ (field)
11.5
R4 R = Peer reviewed scientific publications 4 = Verified data
Non-persistent
DT₉₀ (lab at 20 °C)
-
-
-
DT₉₀ (field)
-
-
-
DT₅₀ modelling endpoint
-
-
-
Note
General literature states DT₅₀ 4 days to 18 days (R4)
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
-
-
-
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
-
-
-
Note
-
Water-sediment DT₅₀ (days)
-
-
-
Water 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)
-
H3 H = The US ARS pesticide properties database. Dataset is no longer available. 3 = Unverified data of known source
Slightly mobile
Koc (mL g⁻¹)
700
Notes and range
Best available data
Freundlich
Kf (mL g⁻¹)
-
-
-
Kfoc (mL g⁻¹)
-
1/n
-
Notes and range
-
pH sensitivity
-
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
1.23
Calculated
Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
1.91 X 10-02
Calculated
-
Note
-
Potential for particle bound transport index
Low
Calculated
-
Potential for loss via drain flow
Slightly mobile
Calculated
-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk
-
-
-
Bio-concentration factor
BCF (l kg⁻¹)
2.4
J4 J = Pesticide Action Network database (click here ) 4 = Verified data
(Other literature Log BCF range -1.5-0.8 (R3))
Low potential
CT₅₀ (days)
1.7
-
Known metabolites
None
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
2000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Rat
Moderate
Mammals - Short term dietary NOEL
(mg kg⁻¹)
-
-
-
(ppm diet)
-
-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
-
-
-
Birds - Acute LD₅₀ (mg kg⁻¹)
> 4640
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Anas platyrhynchos
Low
Birds - Short term dietary (LC₅₀/LD₅₀)
-
-
-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
-
-
-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)
0.515
R4 R = Peer reviewed scientific publications 4 = Verified data
Eisenia foetida
High
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)
> 100
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
> 100
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
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)
-
-
-
-
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)
> 0.44
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Lepomis macrochirus
Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
0.025
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
Danio rerio 30 day
Moderate
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
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
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
Environmental fate
Ecotoxicity
Warning:
