Select Option
A to Z
Terms & Conditions
Support Information
Purchasing & Other Services
Video User Guides

metribuzin (Ref: DPX G2504)
** metribuzine ** DIC 1468 ** AE F055208 ** Translations

Environmental Fate - Ecotoxicology - Human Health - A to Z Index - Home

for metribuzin

Description: A pre- and post-emergence herbicide used to control weeds in cereals and a range of other crops

Example pests controlled: Grasses; Broad-leaved weeds

Example applications: Soybeans; Potatoes; Barley, Wheat; Asparagus; Sugarcane; Tomatoes; Peas; Lentils

Availability status: Current

Introduction & key dates: 1968, first reported; 1971, first marketed

EC Regulation 1107/2009 (repealing 91/414):
Status Approved
Dossier rapporteur/co-rapporteur Germany
Date inclusion expires 31/07/2018

Approved for use () or known to be used () in the following European countries:





























Also used in: Australia

General status:
Pesticide type Herbicide
Substance group Triazinone
Minimum active substance purity 930 +/- 20 g/kg
Known relevant impurities EU dossier - None declared
Substance origin Synthetic
Mode of action Selective, systemic with contact and residual activity. Inhibits photosynthesis (photosystem II).
CAS RN 21087-64-9
EC number 244-209-7
CIPAC number 283
US EPA chemical code 101101
Chiral molecule No
Chemical formula C8H14N4OS
International Chemical Identifier key (InChIKey) FOXFZRUHNHCZPX-UHFFFAOYSA-N
International Chemical Identifier (InChI) InChI=1S/C8H14N4OS/c1-8(2,3)5-6(13)12(9)7(14-4)11-10-5/h9H2,1-4H3
Structure diagram/image available? Yes
Molecular mass (g mol-1) 214.29
PIN (Preferred Identification Name) -
IUPAC name 4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one
CAS name 4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one
Other status information Potential groundwater contaminant
Herbicide Resistance Classification (HRAC) C1
Herbicide Resistance Classification (WSSA) 5
Insecticide Resistance Classification (IRAC) Not applicable
Fungicide Resistance Classification (FRAC) Not applicable
Examples of recorded resistance Amaranthus hybridus
Physical state White crystalline solid
Related substances & organisms

Property Value
Example manufacturers & suppliers of products using this active now or historically
  • AgriGuard
  • Bayer CropScience
  • DuPont
  • Greencrop
  • Makhteshim-Agan
Example products using this active
  • Artist
  • Lexone 2
  • Sencorex WG
  • Shotput
  • Sencor
UK LERAP status Buffer probably required in UK - see product label
Formulation and application details Often supplied as wettable powders, liquid suspensions or water-dispersible granules.


for metribuzin

Property Value Source/Quality Score/Other Information Interpretation
Solubility - In water at 20oC (mg l-1) 1165 A5 High
Solubility - In organic solvents at 20oC (mg l-1) 820 A5 - n-Heptane -
60000 A5 - Xylene -
250000 A5 - Ethyl acetate -
449400 A5 - Acetone -
Melting point (oC) 125 A5 -
Boiling point (oC) Decomposes before boiling A5 -
Degradation point (oC) 125 A5 -
Flashpoint (oC) Not expected to self ignite; Not highly flammable A5 -
Octanol-water partition coefficient at pH 7, 20oC P 4.47 X 1001 Calculated -
Log P 1.65 A5 Low
Bulk density (g ml-1)/Specific gravity 1.26 A5 -
Dissociation constant (pKa) at 25oC 0.99 Q3 - @ 25degC -
Note: Strong acid, pKb = 13
Vapour pressure at 25oC (mPa) 0.121 A5 Volatile
Henry's law constant at 25oC (Pa m3 mol-1) 2.00 X 10-05 A5 Non-volatile
Henry's law constant at 20oC (dimensionless) 1.49 X 10-09 Q2 Non-volatile
GUS leaching potential index 2.57 Calculated Transition state
SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate Value 7.64 X 10-02 Calculated -
Note -
Potential for particle bound transport index - Calculated Low
Maximum UV-vis absorption L mol-1 cm-1 294nm = 8175 (mean) A5 -
Surface tension (mN m-1) 63.1 A5 at 20oC -

Property Value Source/Quality Score/Other Information Interpretation
Soil degradation (days) (aerobic) DT50 (typical) 11.5 A5 Non-persistent
DT50 (lab at 20oC) 11.5 A5 Non-persistent
DT50 (field) 19 Y4 Non-persistent
DT90 (lab at 20oC) 49 A5 -
DT90 (field) - - -
Note EU dossier DT50 range 5.3-17.7 days, DT90 range 17.6-91.8 days
Plant matrix DT50 (days) Value 5 A4 -
Note -
Aqueous photolysis DT50 (days) at pH 7 Value 0.2 C4 Fast
Note -
Aqueous hydrolysis DT50 (days) at 20oC and pH 7 Value Stable A5 Very persistent
Note Stable pH 4 to pH 9 at 25 degC over 34 days. Stable pH 4 and pH 7 at 50 degC, some hydrolysis at pH 9 and 50 degC but slow
Water-sediment DT50 (days) 50 A5 Moderately fast
Water phase only DT50 (days) 41 A5 Stable

Soil adsorption and mobility:
Property Value Source/Quality Score/Other Information Interpretation
Linear Kd - - -
Koc -
Notes and range -
Freundlich Kf 0.959 A5 Mobile
Kfoc 37.92
1/n 1.08
Notes and range EU dossier kf range 0.018-1.9, Kfoc range 3.14-81.5 mL/g, 1/n 0.89-1.52, Soils=7
pH sensitivity No

Key metabolites:
Metabolite Formation medium Estimated maximum occurrence fraction 91/414 relevancy
diketo-metribuzin (Ref: AE 1344183) Soil   0.097   Minor fraction, Relevant
desaminodiketometribuzin Soil   0.167   Major fraction, Relevant

Other known metabolites:
Metabolite name and reference Aliases Formation medium / Rate Estimated maximum occurrence fraction Metabolising enzymes
4-amino-6-(1,1-dimethylethyl)-1,2,4-triazine-5(4H)-one desmethylthio-metribuzin Groundwater - -
6-tert-butyl-4,5-dihydro-1,2,4-triazin-5-one-3-mercapturic acid - Groundwater - -
6-(1-hidroxy-1-methyl-ethyl)-3-methylsulfanyl-4H-[1,2,4]-triazine-5-one t-BuOH-desamino-metribuzin; metribuzin metabolite M05 Rat - -
4-methyl-6-(1,1-dimethylethyl)-1,2,4-triazine-3,5(2H,4H)-dione 4-methyl-desamino-diketo-metribuzin; metribuzin metabolite M17 Groundwater - -


for metribuzin

Property Value Source/Quality Score/Other Information Interpretation
Bio-concentration factor BCF (l kg-1) 10 A5 Low potential
CT50 (days) Not available -
Mammals - Acute oral LD50 (mg kg-1) 322 A5 Rat Moderate
Mammals - Short term dietary NOEL (mg kg-1) 2.2 A5 Rat High
(ppm diet) - -
Birds - Acute LD50 (mg kg-1) 164 A5 Colinus virginianus Moderate
Birds - Short term dietary (LC50/LD50) > 359 mg kg bw-1 day-1 A5 Colinus virginianus -
Fish - Acute 96 hour LC50 (mg l-1) 74.6 A5 Oncorhynchus mykiss Moderate
Fish - Chronic 21 day NOEC (mg l-1) 5.6 A5 Oncorhynchus mykiss, growth Moderate
Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) 49 A5 Daphnia magna Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) 0.32 A5 Daphnia magna 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) 0.008 A5 Lemna gibba High
Non-target plants 15.7 A5 Brassica napus, Seedling emergence, ER50, Seedling emergence, ER50, as g/ha -
12.3 A5 Brassica napus, Vegetative vigour, ER50, as g/ha -
Algae - Acute 72 hour EC50, growth (mg l-1) 0.02 A5 Scenedemus subspicatus Moderate
Algae - Chronic 96 hour NOEC, growth (mg l-1) 0.019 Q2 Unknown species Moderate
Honeybees Contact acute 48 hour LD50 (μg bee-1) 200 A5 Low
Oral acute 48 hour LD50 (μg bee-1) 166 A5 Low
Unknown mode acute 48 hour LD50 (μg bee-1) - - -
Earthworms - Acute 14 day LC50 (mg kg-1) 427 A5 Eisenia foetida Moderate
Earthworms - Chronic 14 day NOEC, reproduction (mg kg-1) > 5.25 A4 Eisenia foetida, 56 day Moderate
Other soil macro-organisms - e.g. Collembola LR50 / EC50 / NOEC / % Effect - - -
Other arthropod (1) LR50 g ha-1 65.9 48 hour
A5 Aphidius rhopalosiphi, adult
% Effect - - -
Other arthropod (2) LR50 g ha-1 72.9 7 day
A5 Typhlodromus pyri, protonymph
% Effect - - -
Soil micro-organisms Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect
Dose: Not stated, 28 days
Mesocosm study data NOEAEC mg l-1 - - -
NOEAEC mg l-1 - - -


for metribuzin

Property Value Source/Quality Score/Other Information Interpretation
Threshold of Toxicological Concern (Cramer Class) High (class III) - -
Mammals - Acute oral LD50 (mg kg-1) 322 A5 Rat Moderate
Mammals - Dermal LD50 (mg kg-1 body weight) > 5000 A5 Rat -
Mammals - Inhalation LC50 (mg l-1) 2.05 A5 Rat -
Other Mammal toxicity endpoints - -
ADI - Acceptable Daily Intake (mg kg-1bw day-1) 0.013 A5 Rat, SF=100 -
ARfD - Acute Reference Dose (mg kg-1bw day-1) 0.02 A5 SF=100 -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) 0.02 A5 SF=100 -
Dermal penetration studies (%) 50.0-100.0 A5 concentration dependant -
Dangerous Substances Directive 76/464 - - -
Exposure Limits - - -
Exposure Routes Public No unacceptable risks to bystanders identified
Occupational Minimal risk for operators using protection clothing and equipment
European MRLs Click here for the EU MRL pesticide database
Drinking Water MAC (μg l-1) - - -

Health issues:
Carcinogen Mutagen Endocrine disrupter Reproduction / development effects Cholinesterase inhibitor Neurotoxicant


Respiratory tract irritant Skin irritant Skin sensitiser Eye irritant Phototoxicant





General human health issues Thyroid toxicant

: Yes, known to cause a problem
: No, known not to cause a problem
: Possibly, status not identified
- : No data found

Handling issues:
Property Value Source/Quality Score/Other Information Interpretation
General Not explosive
IMDG Transport Code is usually 9
CLP classification 2013 Health: H302
Environment: H400, H410
EC Risk Classification Xn - Harmful: R22
N - Dangerous for the environment: R50, R53
EC Safety Classification S2, S60, S61
WHO Classification II - Moderately hazardous
US EPA Classification (formulation) III - Caution - Slightly toxic
UN Number Usually 3077
Waste disposal & packaging Packaging Group III (minor danger)


for metribuzin

Language Name
English metribuzin
French metribuzine
German Metribuzin
Danish metribuzin
Italian metribuzin
Spanish metribuzina
Greek metribuzin
Slovenian metribuzin
Polish metrybuzyna
Swedish metribuzin
Hungarian metribuzin
Dutch metribuzine

Record last updated: Saturday 19 March 2016