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Chloridazon (Ref: BAS 119H)
Last updated: 22/08/2024
(Also known as: pyrazon; pyrazone; PAC; chloridazone)

SUMMARY
Choridazon is a herbicide for broad-leaved weeds and grass control. It has a moderate aqueous solubility and is not considered to be volatile. It is moderately persistent in soil system and can also be persistent in water systems under some conditions. It has a low oral mammalian toxicity and whilst it is a recognised skin and eye irritant no chronic health impacts have been identified. It shows moderate to low ecotoxicity to most species.
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:
GUS: Transition state; Drainflow: Moderately mobile
Ecotoxicity
Moderate alert:
Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Fish chronic ecotoxicity: Moderate; Daphnia chronic ecotoxicity: Moderate
Human health
Moderate alert:
Mammals chronic toxicity: Moderate; Reproduction/development effects; Neurotoxicant
GENERAL INFORMATION
Description
A residual pyridazinone herbicide for control of weeds in beet and other crops crops
Example pests controlled
Broad-leaf and grass weeds including blackgrass, canary grass and wild oats
Example applications
Sugarbeet; Fodder beet; Red beet; Mangels; Onions; Shallots; Garlic; Ornamentals
Efficacy & activity
-
Availability status
Current
Introduction & key dates
1964, 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
Germany/Poland
Date EC 1107/2009 inclusion expires
Not applicable
EU Candidate for substitution (CfS)
No
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
ISIceland
NONorway
                 
Additional information
Also used in
Australia
Chemical structure
Isomerism
Isomeric - the 4-amino-5-chloro-isomer is a common impurity
Chemical formula
C₁₀H₈ClN₃O
Canonical SMILES
C1=CC=C(C=C1)N2C(=O)C(=C(C=N2)N)Cl
Isomeric SMILES
No data
International Chemical Identifier key (InChIKey)
WYKYKTKDBLFHCY-UHFFFAOYSA-N
International Chemical Identifier (InChI)
InChI=1S/C10H8ClN3O/c11-9-8(12)6-13-14(10(9)15)7-4-2-1-3-5-7/h1-6H,12H2
2D structure diagram/image available?
Yes
Cambridge Crystallographic Data Centre diagrams
Common Name Relationship Link
chloridazon -
General status
Pesticide type
Herbicide
Substance groups
Pyridazinone herbicide
Minimum active substance purity
920 g kg⁻¹
Known relevant impurities
EU dossier - 5-chloro isomer <60 g/Kg
Substance origin
Synthetic
Mode of action
Selective, systemic. Inhibits photosynthesis (photosystem II).
CAS RN
1698-60-8
EC number
216-920-2
CIPAC number
111
US EPA chemical code
069601
PubChem CID
15546
CLP index number
606-035-00-3
Molecular mass
221.6
PIN (Preferred Identification Name)
5-amino-4-chloro-2-phenylpyridazin-3(2H)-one
IUPAC name
5-amino-4-chloro-2-phenylpyridazin-3(2H)-one
CAS name
5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone
Other status information
-
Relevant Environmental Water Quality Standards
-
Herbicide Resistance Class (HRAC MoA class)
C1
Herbicide Resistance Class (WSSA MoA class)
5
Insecticide Resistance Class (IRAC MoA class)
Not applicable
Fungicide Resistance Class (FRAC MOA class)
Not applicable
Examples of recorded resistance
-
Physical state
Colourless crystalline solid
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
  • AgriGuard
  • BASF
  • Nufarm
  • Sipcam
  • Du Pont
Example products using this active
  • Ashlade CP
  • Magnum
  • Pyramin DF
  • Takron
  • Questar
  • BREK
Formulation and application details
Supplied in a variety of formulations including suspension concentrates and wettable powders
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
422
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
Moderate
Solubility - In organic solvents at 20 °C (mg l⁻¹)
15100
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
Methanol
-
3700
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
Ethyl acetate
-
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
Toluene
-
190
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
Dichloromethane
-
Melting point (°C)
206
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
A3 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 )
3 = Unverified data of known source
-
Degradation point (°C)
360
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)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
1.55 X 1001 Calculated -
Log P
1.19
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
Low
Fat solubility of residues
Solubility
Insoluble
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
-
Data type
Regulatory data
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
-
Density (g ml⁻¹)
1.51
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
-
Dissociation constant pKa) at 25 °C
3.38
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
-
Very weak acid
Vapour pressure at 20 °C (mPa)
1.0 X 10-06
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
Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
5.30 X 10-10
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-volatile
Volatilisation as max % of applied dose lost
From plant surface
- - -
From soil surface
- - -
Maximum UV-vis absorption L mol⁻¹ cm⁻¹
210nm = 18577, 229nm = 25043, 286nm = 10088
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)
72.0
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
Property
Value
Source; quality score; and other information
Interpretation
General biodegradability
-
Soil degradation (days) (aerobic)
DT₅₀ (typical)
31
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here )
4 = Verified data
Moderately persistent
DT₅₀ (lab at 20 °C)
43.1
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
Moderately persistent
DT₅₀ (field)
18.6
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-persistent
DT₉₀ (lab at 20 °C)
78.4
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
Moderately persistent
DT₉₀ (field)
60.8
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
-
DT₅₀ modelling endpoint
- - -
Note
EU dossier lab studies DT₅₀ range 8.6-173.9 days (normalised), DT₉₀ range 50-140 days (normalised); field studies DT₅₀ range 3-105 days (normalised), DT₉₀ range 9-349 days (normalised); Other sources: DT₅₀ 21.0 days (DW3)
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
40
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
Stable
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
Stable
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
Stable
Note
Stable at all pH for over 30 days
Water-sediment DT₅₀ (days)
137
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
Slow
Water phase only DT₅₀ (days)
51.5
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
Stable
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)
-
DW3 DW = Don Wauchope personal database for Pka data: Wauchope, R. D. and Edwards, J. Dissociation constants for pesticide active ingredients: a database and comparison with predicted values. Dataset is no longer available.
3 = Unverified data of known source
Moderately mobile
Koc (mL g⁻¹)
120
Notes and range
-
Freundlich
Kf (mL g⁻¹)
1.1
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
Moderately mobile
Kfoc (mL g⁻¹)
199
1/n
0.845
Notes and range
EU dossier Kf range 0.2-3.6 mL g⁻¹, Kfoc range 89-340 mL g⁻¹, 1/n range 0.568-1.03, Soils=5
pH sensitivity
No
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
2.16 Calculated Transition state
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
7.56 X 10-02 Calculated -
Note
-
Potential for particle bound transport index
Low Calculated -
Potential for loss via drain flow
Moderately mobile Calculated -
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk
7.0
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
Calculated using the Atkinson method.
Below the level of concern for long-range air transport
Bio-concentration factor
BCF (l kg⁻¹)
12
P4 P = Other non-EU, UK or US Governments and Regulators
4 = Verified data
Low potential
CT₅₀ (days)
Not available -
Known soil metabolites
Metabolite
Major/Minor fraction
Estimated maximum occurrence fraction
Notes
5-amino-4-chloro-3(2H)-pyridazinone
Major fraction 0.169 BASF verified
5-amino-4-chloro-2-methyl-3(2H)-pyridazinone
Minor fraction - BASF verified
5-(1-amino-1-desoxyglucopyranosyl)-4-chloropyridazin-3(2H)-one (metabolite A)
- - -
Known groundwater metabolites
Metabolite
EC SANCO/221/2000 relevancy
ADI (mg kg⁻¹ bodyweight day⁻¹)
WHO drinking water guidance value (μg L⁻¹ day⁻¹)
5-amino-4-chloro-3(2H)-pyridazinone
Not relevant 0.015 90
5-amino-4-chloro-2-methyl-3(2H)-pyridazinone
Not relevant 0.01 60
Other known metabolites
Metabolite name and reference
Aliases
Formation medium / Rate
Estimated maximum occurrence fraction
- chloridazon metabolite B-glucoside Plant -
5-amino-4-chloro-2-methyl-3(2H)-pyridazinone
Note: DT50 soil 144 days
chloridazon metabolite B-1 Plant -
5-amino-4-chloro-2-(4-hydroxyphenyl)-3(2H)-pyridazinone 4-OH-chloridazon; BH 119-4-OH Animal; Rat (Urine, Bile, Faeces) -
5-amino-4-chloro-2-(4-sulfatophenyl)-3(2H)-pyridazinone sulfate conjugate of BH 119-4-OH Animal; Rat -
5-amino-2-phenyl-3(2H)-pyridazinone deschloro-chloridazon Animal -
5-amino-2-(4-sulfatophenyl)-3(2H)-pyridazinone sulfate conjugate of deschloro-chloridazon Rat -
- glucuronide of BH 119-4-OH Rat -
- 5-(1-amino-1-desoxyglucopyranosyl)-4-chloropyridazin-3(2H)-one; chloridazon metabolite A Animal; Plant; Surface water -
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
2140
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
Rat
Low
Mammals - Short term dietary NOEL
(mg kg⁻¹)
16
L2 L = Pesticide manuals and hard copy reference books / other sources
2 = Unverified data of unknown source
Rat 2 yr
High
(ppm diet)
- -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
148
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
Rat Reproductive NOAEL
Moderate
Birds - Acute LD₅₀ (mg kg⁻¹)
> 2000
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
Colinus virginianus
Low
Birds - Short term dietary (LC₅₀/LD₅₀)
> 1318 mg kg bw⁻¹ day⁻¹
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
Colinus virginianus
-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
21.8
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
Colinus virginianus NOAEL
Moderate
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)
> 1000
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
Eisenia foetida
Low
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
- - -
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: 26 mg kg⁻¹ soil
-
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)
> 200
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
Apis mellifera
Low
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
> 200
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
Apis mellifera
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) as % Mortality at dose 3.82 kg ha⁻¹
7.1
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
Chrysoperla carnea Larva
-
Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹
> 4000
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
Aphidius rhopalosiphi
-
Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹
4000
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
Typhlodromus pyri
-
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)
41.3
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
Oncorhynchus mykiss
Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
3.16
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
Oncorhynchus mykiss
Moderate
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
132.0
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
Daphnia magna
Low
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
6.23
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
Daphnia magna
Moderate
Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (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)
- - -
Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)
- - -
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)
> 3.16
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
Lemna gibba
Moderate
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
> 3.0
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
Pseudokirchneriella subcapitata
Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
0.73
Q2 Q = Miscellaneous data from online sources
2 = Unverified data of unknown source
Unknown species
Moderate
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)
2140
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
Rat
Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
2000
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
Rat
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
> 5.4
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
Rat 4 hr
-
Other Mammal toxicity endpoints
- - -
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)
0.1
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
-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
None allocated
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
-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)
- - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)
0.2
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
-
Dermal penetration studies (%)
4
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
Acceptable risk for bystanders for proposed uses
Occupational
Acceptable risk for operators and other workers for proposed uses
MRLs
European
EU MRL pesticide database 
Great Britain
GB MRL Register 
Notes
EU expected to amend MRL in early 2023
Drinking Water Standards
- - -
Drinking Water MAC (μg l⁻¹)
- - -
Mammalian dose elimination route and rate
- - -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
XNo, known not to cause a problem
A3 A = Chromosome aberration (EFSA database)
3 = Negative
;
B3 B = DNA damage/repair (EFSA database)
3 = Negative
;
C3 C = Gene mutation (EFSA database)
3 = Negative
;
D0 D = Genome mutation (EFSA database)
0 = No data
;
E0 E = Unspecified genotoxicity type (miscellaneous data source)
0 = No data
No data found
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
?Possibly, status not identified
XNo, known not to cause a problem
?Possibly, status not identified
Respiratory tract irritant Skin irritant Skin sensitiser
XNo, known not to cause a problem
Yes, known to cause a problem
?Possibly, status not identified
Eye irritant Phototoxicant  
Yes, known to cause a problem
No data found  
General human health issues
No further information available
Handling issues
Property
Value and interpretation
General
Not explosive
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable
CLP classification 2013
Health: H317
Environment: H400, H410
WHO Classification
III (Slightly hazardous)
UN Number
-
Waste disposal & packaging
Packaging Group III (minor danger)
Shelf-life, storage, stability and reactivity
-
TRANSLATIONS
Language
Name
English
chloridazon
French
chloridazone
German
Chloridazon
Danish
chloridazon
Italian
chloridazon
Spanish
cloridazon; pirazona
Greek
-
Polish
chlorydazon
Swedish
kloridazon
Hungarian
chloridazon
Dutch
chloridazon
Norwegian
-

Record last updated: 22/08/2024
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