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paraquat (Ref: PP 148)
** orthoparaquat ** PP 910 ** Translations

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

for paraquat

Description: A herbicide used to control common weeds in a wide range of agricultural and amenity situations

Example pests controlled: Broad-leaved weeds including cocksfoot; Grasses including wild oats, Yorkshire fog grass, ryegrass, fescue

Example applications: Rice; Lucerne; Beans & peas; Hops; Vineyards; Potaoes; Non-cropped areas such as roadways, paths

Availability status: Current

Introduction & key dates: 1962

EC Regulation 1107/2009 (repealing 91/414):
Status Not approved
Dossier rapporteur/co-rapporteur UK
Date inclusion expires Expired

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





























Also used in: Australia, USA, Canada, Mexico, Brazil, Japan, India, China, Indonesia, Thailand, New Zealand

General status:
Pesticide type Herbicide
Substance group Bipyridylium
Minimum active substance purity -
Known relevant impurities EU dossier - free 4,4-bipyridyl
Substance origin Synthetic
Mode of action Broad-spectrum, non-residual activity with contact and some desiccant action. Photosystem I (electron transport) inhibitor.
CAS RN 4685-14-7
EC number 217-615-7
CIPAC number 56
US EPA chemical code -
Chiral molecule No
Chemical formula C12H14N2
SMILES c2cc(c1cc[n+](cc1)C)cc[n+]2C
International Chemical Identifier key (InChIKey) INFDPOAKFNIJBF-UHFFFAOYSA-N
International Chemical Identifier (InChI) InChI=1S/C12H14N2/c1-13-7-3-11(4-8-13)12-5-9-14(2)10-6-12/h3-10H,1-2H3/q+2
Structure diagram/image available? Yes
Molecular mass (g mol-1) 186.25
PIN (Preferred Identification Name) -
IUPAC name 1,1'-dimethyl-4,4'-bipyridinium
CAS name 1,1'-dimethyl-4,4'-bipyridinium
Other status information PAN Dirty Dozen; Chemical subject to PIC regulations
Herbicide Resistance Classification (HRAC) D
Herbicide Resistance Classification (WSSA) 22
Insecticide Resistance Classification (IRAC) Not applicable
Fungicide Resistance Classification (FRAC) Not applicable
Examples of recorded resistance Lolium rigidum
Physical state Colourless to pale yellow crystalline solid
Related substances & organisms

Property Value
Example manufacturers & suppliers of products using this active now or historically
  • AgriGuard
  • Clayton
  • Syngenta
Example products using this active
  • AgriGuard Paraquat
UK LERAP status None
Formulation and application details Often supplied as a soluble concentrate that is mixed with water and used as a spray.


for paraquat

Property Value Source/Quality Score/Other Information Interpretation
Solubility - In water at 20oC (mg l-1) 620000 A5 High
Solubility - In organic solvents at 20oC (mg l-1) 143000 A5 - Methanol -
100 A5 - Acetone -
100 A5 - Toluene -
100 A5 - Hexane -
Melting point (oC) - - -
Boiling point (oC) - - -
Degradation point (oC) - - -
Flashpoint (oC) - - -
Octanol-water partition coefficient at pH 7, 20oC P 3.16 X 10-05 Calculated -
Log P -4.5 A5 Low
Bulk density (g ml-1)/Specific gravity 1.5 A5 -
Dissociation constant (pKa) at 25oC Not applicable A5 -
Note: No dissociation
Vapour pressure at 25oC (mPa) 0.01 A3 Volatile
Henry's law constant at 25oC (Pa m3 mol-1) 4.00 X 10-12 A5 Non-volatile
Henry's law constant at 20oC (dimensionless) 1.23 X 10-12 Calculated Non-volatile
GUS leaching potential index -7.40 Calculated Low leachability
SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate Value 5.35 X 10-03 Calculated -
Note Estimated concentrations of chemicals with Koc values greater than 9995 ml g-1 are beyond the scope of the regression data used in SCI-GROW development. If there are concerns for such chemicals, a higher tier groundwater exposure assessment should be considered, regardless of the concentration returned by SCI-GROW
Potential for particle bound transport index - Calculated High
Maximum UV-vis absorption L mol-1 cm-1 290nm A5 -
Surface tension (mN m-1) - - -

Property Value Source/Quality Score/Other Information Interpretation
Soil degradation (days) (aerobic) DT50 (typical) 3000 A5 Very persistent
DT50 (lab at 20oC) 5000 Y3 Very persistent
DT50 (field) 2800 A5 Very persistent
DT90 (lab at 20oC) - - -
DT90 (field) - - -
Note Field studies DT50 range 7-8 years (UK)
Plant matrix DT50 (days) Value - - -
Note -
Aqueous photolysis DT50 (days) at pH 7 Value Stable A5 Stable
Note -
Aqueous hydrolysis DT50 (days) at 20oC and pH 7 Value Stable A5 Very persistent
Note Stable pH 5 to pH 9, 30 days at 25 and 40 degC
Water-sediment DT50 (days) Stable Q2 Stable
Water phase only DT50 (days) 10 Q2 Moderately fast

Soil adsorption and mobility:
Property Value Source/Quality Score/Other Information Interpretation
Linear Kd - A3 Non-mobile
Koc 1000000
Notes and range -
Freundlich Kf - - -
Kfoc -
1/n -
Notes and range -
pH sensitivity -


for paraquat

Property Value Source/Quality Score/Other Information Interpretation
Bio-concentration factor BCF (l kg-1) Low risk A5 Based on LogP < 3 Low potential
CT50 (days) - -
Mammals - Acute oral LD50 (mg kg-1) 110 G4 Rat Moderate
Mammals - Short term dietary NOEL (mg kg-1) - A5 Rat -
(ppm diet) > 100 -
Birds - Acute LD50 (mg kg-1) 35 A4 Unknown species High
Birds - Short term dietary (LC50/LD50) 698 mg kg feed-1 A4 unknown species -
Fish - Acute 96 hour LC50 (mg l-1) 19 A5 Oncorhynchus mykiss Moderate
Fish - Chronic 21 day NOEC (mg l-1) - - -
Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) 4.4 A5 Daphnia magna Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) 0.12 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) 0.367 A5 Chironomus riparius Moderate
Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg-1) > 100 A5 Chironomus riparius Low
Aquatic plants - Acute 7 day EC50, biomass (mg l-1) 0.037 A5 Lemna gibba Moderate
Non-target plants - - -
- - -
Algae - Acute 72 hour EC50, growth (mg l-1) 0.00023 A5 Raphidocelis subcapitata High
Algae - Chronic 96 hour NOEC, growth (mg l-1) - - -
Honeybees Contact acute 48 hour LD50 (μg bee-1) 9.26 A5 Moderate
Oral acute 48 hour LD50 (μg bee-1) > 9.06 A5 Moderate
Unknown mode acute 48 hour LD50 (μg bee-1) - - -
Earthworms - Acute 14 day LC50 (mg kg-1) > 1000 A5 Eisenia foetida Low
Earthworms - Chronic 14 day NOEC, reproduction (mg kg-1) - - -
Other soil macro-organisms - e.g. Collembola LR50 / EC50 / NOEC / % Effect - - -
Other arthropod (1) LR50 g ha-1 - - -
% Effect 0 Mortality
Dose: 0.01 kg ha-1
A5 Pardosa spp., adult
Other arthropod (2) LR50 g ha-1 - - -
% Effect 0 Mortality
Dose: 0.01 kg ha-1
A5 Aleochara bilineata, adult
Soil micro-organisms Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect
Dose: 720 kg ha-1, 1 year
Mesocosm study data NOEAEC mg l-1 - - -
NOEAEC mg l-1 - - -


for paraquat

Property Value Source/Quality Score/Other Information Interpretation
Threshold of Toxicological Concern (Cramer Class) High (class III) - -
Mammals - Acute oral LD50 (mg kg-1) 110 G4 Rat Moderate
Mammals - Dermal LD50 (mg kg-1 body weight) > 200 A4 Rat -
Mammals - Inhalation LC50 (mg l-1) 0.6 A5 Rat -
Other Mammal toxicity endpoints - -
ADI - Acceptable Daily Intake (mg kg-1bw day-1) 0.004 A5 Dog, SF=100 -
ARfD - Acute Reference Dose (mg kg-1bw day-1) 0.005 A5 Dog, SF=100 -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) 0.0004 A5 Dog, 90 day, SF=100 -
Dermal penetration studies (%) 0.5 A5 -
Dangerous Substances Directive 76/464 [No unacceptable risks to bystanders identified] - -
Exposure Limits [LT TWA 8hr: 0.1 mg/m3] Occupation Exposure -
Exposure Routes Public No unacceptable risks to operators or other workers identified
Occupational -
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 Potential liver, kidney, stomach, intestine and respiratory system 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 or oxidising
IMDG Transport Code is usually 6.1
CLP classification 2013 Health: H301, H311, H315, H319, H330, H335, H372
Environment: H400, H410
EC Risk Classification T+ - Very toxic: R26
T - Toxic: R24/25, R48/25
Xi - Irritant: R36/37/38
N - Dangerous for the environment: R50, R53
EC Safety Classification S1/2, S22, S28, S36/37/39, S45, S60, S61
WHO Classification II - Moderately hazardous
US EPA Classification (formulation) No consensus across products or no products available - -
UN Number 2781
Waste disposal & packaging Packaging Group II (medium danger)


for paraquat

Language Name
English paraquat
French paraquat
German Paraquat
Danish paraquat
Italian paraquat
Spanish paracuat
Greek -
Slovenian parakvat
Polish parakwat
Swedish -
Hungarian -
Dutch -

Record last updated: Thursday 19 November 2015