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paraquat dichloride
** methyl viologen ** Translations

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for paraquat dichloride

Description: A herbicide used to control common weeds and grasses 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: Unknown

Introduction & key dates: -

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

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





























General status:
Pesticide type Herbicide
Substance group Quarternary ammonium compound
Minimum active substance purity -
Known relevant impurities EU dossier - free 4,4-bipyridyl 0.2%
Substance origin Synthetic
Mode of action Broad-spectrum, non-residual activity with contact and some desiccant action. Photosystem I (electron transport) inhibitor.
CAS RN 1910-42-5
EC number 217-615-7
CIPAC number -
US EPA chemical code 061601
Chiral molecule No
Chemical formula C12H14Cl2N2
SMILES c1(c2cc[n+](C)cc2)cc[n+](C)cc1.[ClH-].[ClH-]
International Chemical Identifier key (InChIKey) FIKAKWIAUPDISJ-UHFFFAOYSA-L
International Chemical Identifier (InChI) InChI=1S/C12H14N2.2ClH/c1-13-7-3-11(4-8-13)12-5-9-14(2)10-6-12;;/h3-10H,1-2H3;2*1H/q+2;;/p-2
Structure diagram/image available? Yes
Molecular mass (g mol-1) 257.16
PIN (Preferred Identification Name) 1,1'-dimethyl-[4,4'-bipyridine]-1,1'-diium dichloride
IUPAC name 1,1'-dimethyl-4,4'-bipyridinium dichloride
CAS name 1,1'-dimethyl-4,4'-bipyridinium dichloride
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 off-white crystalline solid
Related substances & organisms -

Property Value
Example manufacturers & suppliers of products using this active now or historically
  • Syngenta
  • ICI Plant Protection
  • Pillar International
  • Inquinosa
Example products using this active
  • Gramoxone Extra
  • Gramoxone Max
  • Cyclone
  • Pathclear
UK LERAP status No UK approval for use or outside scope
Formulation and application details Usually formulated as a soluble concentrate or aqueous liquid.


for paraquat dichloride

Property Value Source/Quality Score/Other Information Interpretation
Solubility - In water at 20oC (mg l-1) 620000 E4 High
Solubility - In organic solvents at 20oC (mg l-1) 100 A4 - Acetone -
100 A4 - Toluene -
100 A4 - Ethyl acetate -
100 A4 - Hexane -
Melting point (oC) Decomoses before melting A5 - -
Boiling point (oC) Decomposes before boiling A5 -
Degradation point (oC) 340 A5 -
Flashpoint (oC) Not expected to self ignite; Not highly flammable A5 -
Octanol-water partition coefficient at pH 7, 20oC P 3.16 X 10-05 Calculated -
Log P -4.5 E4 Low
Bulk density (g ml-1)/Specific gravity 1.5 E4 -
Dissociation constant (pKa) at 25oC Not applicable E4 -
Note: No dissociation
Vapour pressure at 25oC (mPa) 0.01 E4 Volatile
Henry's law constant at 25oC (Pa m3 mol-1) 4.0 X 10-09 E4 Non-volatile
Henry's law constant at 20oC (dimensionless) 1.70 X 10-12 Calculated Non-volatile
GUS leaching potential index -3.48 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) 365 E4 Very persistent
DT50 (lab at 20oC) 365 E4 Very persistent
DT50 (field) 365 E4 Very persistent
DT90 (lab at 20oC) - - -
DT90 (field) - - -
Note Stable and persistent, General literature DT50 up to 20 years
Plant matrix DT50 (days) Value 30 A4 -
Note -
Aqueous photolysis DT50 (days) at pH 7 Value Stable E4 Stable
Note Stable at all relevant wavelengths
Aqueous hydrolysis DT50 (days) at 20oC and pH 7 Value Stable E4 Very persistent
Note Stable at all relevant pHs
Water-sediment DT50 (days) - - -
Water phase only DT50 (days) - - -

Soil adsorption and mobility:
Property Value Source/Quality Score/Other Information Interpretation
Linear Kd - A5 Non-mobile
Koc 100000
Notes and range EU dossier Koc range 8400-40000000 mL/g
Freundlich Kf 3240 R4 Non-mobile
Kfoc 228537
1/n 2.9
Notes and range Kf range 717-6260 mL/g; Kfoc range 14340-581000 mL/g; 1.n range 1.96-4.0, Soils=9
pH sensitivity None, adsorption correlates to soil clay content


for paraquat dichloride

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) - - -
(ppm diet) - -
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) 15 E4 Oncorhynchus mykiss Moderate
Fish - Chronic 21 day NOEC (mg l-1) - - -
Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) 1.2 E4 Daphnia magna Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) - - -
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) 0.088 E4 Lemna gibba Moderate
Non-target plants - - -
- - -
Algae - Acute 72 hour EC50, growth (mg l-1) 0.32 E4 Raphidocelis subcapitata Moderate
Algae - Chronic 96 hour NOEC, growth (mg l-1) - - -
Honeybees Contact acute 48 hour LD50 (μg bee-1) - - -
Oral acute 48 hour LD50 (μg bee-1) - - -
Unknown mode acute 48 hour LD50 (μg bee-1) > 48 E3 Moderate
Earthworms - Acute 14 day LC50 (mg kg-1) > 1000 A4 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 - - -
Other arthropod (2) LR50 g ha-1 - - -
% Effect - - -
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 dichloride

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) - - -
Mammals - Inhalation LC50 (mg l-1) - - -
Other Mammal toxicity endpoints - -
ADI - Acceptable Daily Intake (mg kg-1bw day-1) 0.004 A4 Dog, SF=100 -
ARfD - Acute Reference Dose (mg kg-1bw day-1) 0.005 A4 Dog, SF=100 -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) 0.0004 A4 Dog, SF=100 -
Dermal penetration studies (%) 0.5 A5 -
Dangerous Substances Directive 76/464 - - -
Exposure Limits [LT TWA 8hr: 0.1 mg/m3] Occupation Exposure -
Exposure Routes Public No unacceptable risks to bystanders identified
Occupational No unacceptable risks to operators or other workers identified
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
May damage lungs if inhaled

: 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 -
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 Usually 2811
Waste disposal & packaging Packaging Group I / II (great / medium danger)


for paraquat dichloride

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English paraquat dichloride
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Record last updated: Monday 17 October 2016