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Paraquat dichloride
Last updated: 25/02/2021
(Also known as: methyl viologen )

GENERAL INFORMATION
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
Efficacy & activity
-
Availability status
Unknown
Introduction & key dates
-
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
UK
Date EC 1107/2009 inclusion expires
Not applicable
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
-
Chemical structure
Isomerism
-
Chemical formula
C₁₂H₁₄Cl₂N₂
Canonical SMILES
C[N+]1=CC=C(C=C1)C2=CC=[N+](C=C2)C.[Cl-].[Cl-]
Isomeric SMILES
No data
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
2D structure diagram/image available?
Yes
Cambridge Crystallographic Data Centre diagrams
Common Name Relationship Link
paraquat dichloride -
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
PubChem CID
15938
Molecular mass
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
Relevant Environmental Water Quality Standards
-
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
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • Gramoxone Extra
  • Gramoxone Max
  • Cyclone
  • Pathclear
Example products using this active
  • Syngenta
  • ICI Plant Protection
  • Pillar International
  • Inquinosa
Formulation and application details
Usually formulated as a soluble concentrate or aqueous liquid
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
620000
E4 E = Manufacturers safety data sheets
4 = Verified data
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
100
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Acetone
-
100
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Toluene
-
100
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Ethyl acetate
-
100
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Hexane
-
Melting point (°C)
Decomoses before melting
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Boiling point (°C)
Decomposes before boiling
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Degradation point (°C)
340
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Flashpoint (°C)
Not expected to self ignite; Not highly flammable
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Octanol-water partition coefficient at pH 7, 20 °C
P
3.16 X 10-05 Calculated -
Log P
-4.5
E4 E = Manufacturers safety data sheets
4 = Verified data
Low
Bulk density (g ml⁻¹)
1.5
E4 E = Manufacturers safety data sheets
4 = Verified data
-
Dissociation constant pKa) at 25 °C
Not applicable
E4 E = Manufacturers safety data sheets
4 = Verified data
-
No dissociation
Vapour pressure at 20 °C (mPa)
0.01
E4 E = Manufacturers safety data sheets
4 = Verified data
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
4.0 X 10-09
E4 E = Manufacturers safety data sheets
4 = Verified data
Non-volatile
Maximum UV-vis absorption L mol⁻¹ cm⁻¹
290nm
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Surface tension (mN m⁻¹)
- - -
Degradation
Property
Value
Source; quality score; and other information
Interpretation
General biodegradability
-
Soil degradation (days) (aerobic)
DT₅₀ (typical)
365
E4 E = Manufacturers safety data sheets
4 = Verified data
Very persistent
DT₅₀ (lab at 20 °C)
365
E4 E = Manufacturers safety data sheets
4 = Verified data
Very persistent
DT₅₀ (field)
365
E4 E = Manufacturers safety data sheets
4 = Verified data
Very persistent
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
DT₅₀ modelling endpoint
- - -
Note
Stable and persistent, General literature DT₅₀ up to 20 years
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
Stable
E4 E = Manufacturers safety data sheets
4 = Verified data
Stable
Note
Stable at all relevant wavelengths
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
Stable
E4 E = Manufacturers safety data sheets
4 = Verified data
Stable
Note
Stable at all relevant pHs
Water-sediment DT₅₀ (days)
- - -
Water phase only DT₅₀ (days)
- - -
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
Non-mobile
Koc
100000
Notes and range
EU dossier Koc range 8400-40000000 mL g⁻¹
Freundlich
Kf
3240
R4 R = Peer reviewed scientific publications
4 = Verified data
Non-mobile
Kfoc
228537
1/n
2.9
Notes and range
Kf range 717-6260 mL g⁻¹; Kfoc range 14340-581000 mL g⁻¹; 1/n range 1.96-4.0, Soils=9
pH sensitivity
None, adsorption correlates to soil clay content
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
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
High Calculated -
Potential for loss via drain flow
Non-mobile Calculated -
ECOTOXICOLOGY
Property
Value
Source; quality score; and other information
Interpretation
Bio-concentration factor
BCF (l kg⁻¹)
Low risk
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
Based on LogP < 3
Low risk
CT₅₀ (days)
- -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
110
G4 G = Extension Toxicology network database EXTOXNET (click here )
4 = Verified data
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)
35
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Unknown species
High
Birds - Short term dietary (LC₅₀/LD₅₀)
698 mg kg feed⁻¹
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Unknown species
-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
15
E4 E = Manufacturers safety data sheets
4 = Verified data
Oncorhynchus mykiss
Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)
2.5
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
Oncorhynchus mykiss 30 day
Moderate
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
1.2
E4 E = Manufacturers safety data sheets
4 = Verified data
Daphnia magna
Moderate
Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
0.01
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 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 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
Chironomus riparius
Moderate
Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)
> 100
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
Chironomus riparius
Low
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)
0.088
E4 E = Manufacturers safety data sheets
4 = Verified data
Lemna gibba
Moderate
Non-target plants
- - -
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
0.32
E4 E = Manufacturers safety data sheets
4 = Verified data
Raphidocelis subcapitata
Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
- - -
Honeybees (Apis spp.)
Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
72
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
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)
> 48
E3 E = Manufacturers safety data sheets
3 = Unverified data of known source
Moderate
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)
> 1000
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Eisenia foetida
Low
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
> 1000
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Eisenia foetida 7 day
Low
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
Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes

Dose: 720 kg ha⁻¹ 1 year
-
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)
110
G4 G = Extension Toxicology network database EXTOXNET (click here )
4 = Verified data
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⁻¹ bw day⁻¹)
0.004
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Dog SF=100
-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
0.005
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Dog SF=100
-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)
- - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)
0.0004
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Dog SF=100
-
Dermal penetration studies (%)
0.5
A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
5 = Verified data used for regulatory purposes
-
Dangerous Substances Directive 76/464
- - -
Exposure Routes
Public
No unacceptable risks to bystanders identified
Occupational
No unacceptable risks to operators or other workers identified
MRLs
European
EU MRL pesticide database 
Notes
-
Drinking Water Standards
- - -
Drinking Water MAC (μg l⁻¹)
- - -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
XNo, known not to cause a problem
A0 A = Chromosome aberration (EFSA database)
0 = No data
;
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
;
E0 E = Unspecified genotoxicity type (miscellaneous data source)
0 = No data
XNo, known not to cause a problem
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
Yes, known to cause a problem
Yes, known to cause a problem
No data found
Eye irritant Phototoxicant  
Yes, known to cause a problem
No data found  
General human health issues
Potential liver, kidney, stomach, intestine and respiratory system toxicant
May damage lungs if inhaled
Handling issues
Property
Value and 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)
UN Number
Usually 2811
Waste disposal & packaging
Packaging Group I / II (great / medium danger)
TRANSLATIONS
Language
Name
English
paraquat dichloride
French
-
German
-
Danish
-
Italian
-
Spanish
-
Greek
-
Polish
-
Swedish
-
Hungarian
-
Dutch
-

Record last updated: 25/02/2021
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