| chloridazon (Ref: BAS 119H) |
 |
Environmental Fate - Ecotoxicology - Human Health - A to Z Index - Home
SUMMARY
Choridazon is a herbicide approved fro use in the EU. 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. GENERAL INFORMATION 
for chloridazon
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
EC Regulation 1107/2009 (repealing 91/414):
| Status | Not approved |
| Dossier rapporteur/co-rapporteur | Germany/Poland |
| Date inclusion expires | Not applicable |
| EU Candidate for substitution (CfS) | No |
| Listed in EU database | Yes |
Approved for use (
) or known to be used (
) in the following European countries: 
AT |
BE |
BG |
CY |
CZ |
DE |
DK |
EE |
EL |
ES |
FI |
FR |
HR |
HU |
IE |
IT |
LT |
LU |
LV |
MT |
NL |
PL |
PT |
RO |
SE |
SI |
SK |
UK |
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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 |
General status:
| Pesticide type | Herbicide | |
| Substance group | Pyridazinone | |
| Minimum active substance purity | 920 g/kg | |
| 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 | |
| Molecular mass (g mol-1) | 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 Classification (HRAC) | C1 | |
| Herbicide Resistance Classification (WSSA) | 5 | |
| Insecticide Resistance Classification (IRAC) | Not applicable | |
| Fungicide Resistance Classification (FRAC) | Not applicable | |
| Examples of recorded resistance | - | |
| Physical state | Colourless crystalline solid | |
| Related substances & organisms | ||
Formulations:
| Property |
Value | |||
| Example manufacturers & suppliers of products using this active now or historically |
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| Example products using this active |
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| UK LERAP status | None | |||
| Formulation and application details | Supplied in a variety of formulations including suspension concentrates and wettable powders. | |||
ENVIRONMENTAL FATE
for chloridazon
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Solubility - In water at 20oC (mg l-1) | 422 | A5 | Moderate | |
| Solubility - In organic solvents at 20oC (mg l-1) | 15100 | A5 - Methanol | - | |
| 3700 | A5 - Ethyl acetate | - | ||
| 100 | A5 - Toluene | - | ||
| 190 | A5 - Dichloromethane | - | ||
| Melting point (oC) | 206 | A5 | - | |
| Boiling point (oC) | Decomposes before boiling | A3 | - | |
| Degradation point (oC) | 360 | A5 | - | |
| Flashpoint (oC) | Not expected to self ignite; Not highly flammable | A5 | - | |
| Octanol-water partition coefficient at pH 7, 20oC | P | 1.55 X 1001 | Calculated | - |
| Log P | 1.19 | A5 | Low | |
| Bulk density (g ml-1)/Specific gravity | 1.51 | A5 | - | |
| Dissociation constant (pKa) at 25oC | 3.38 | V3 | - | |
| Note: Very weak acid | ||||
| Vapour pressure at 20oC (mPa) | 1.0 X 10-06 | A5 | Low volatility | |
| Henry's law constant at 25oC (Pa m3 mol-1) | 5.30 X 10-10 | A5 | Non-volatile | |
GUS leaching potential index  |
2.78 | Calculated | Transition state | |
| SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate |
Value | 2.19 X 10-01 | Calculated | - |
| Note | - | |||
| Potential for particle bound transport index |
- | Calculated | Low | |
| Maximum UV-vis absorption L mol-1 cm-1 | 210nm = 18577, 229nm = 25043, 286nm = 10088 | A5 | - | |
| Surface tension (mN m-1) | 72.0 | A5 | - | |
Degradation:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
General biodegradability | - |
| Soil degradation (days) (aerobic) | DT50 (typical) | 31 | K4 | Moderately persistent |
| DT50 (lab at 20oC) | 43.1 | A5 | Moderately persistent | |
| DT50 (field) | 34.7 | A5 | Moderately persistent | |
| DT90 (lab at 20oC) | 86 | A5 | - | |
| DT90 (field) | 103 | A5 | - | |
| DT50 modelling endpoint | - | - | - | |
| Note | EU dossier lab studies DT50 range 8.6-173.9 days, DT90 range 50-140 days; field studies DT50 range 3-97 days, DT90 range 35-214 days; Other sources: DT50 21.0 days (DW3) | |||
| 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 | 40 | A5 | Stable |
| Note | - | |||
| Aqueous hydrolysis DT50 (days) at 20oC and pH 7 | Value | Stable | A5 | - |
| Note | Stable at all pH for over 30 days | |||
| Water-sediment DT50 (days) | 137 | A5 | Slow | |
| Water phase only DT50 (days) | 51.5 | A5 | Stable | |
Soil adsorption and mobility:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Linear | Kd | - | DW3 | Moderately mobile |
| Koc | 120 | |||
| Notes and range | - | |||
| Freundlich | Kf | 1.1 | A5 | Moderately mobile |
| Kfoc | 199 | |||
| 1/n | 0.845 | |||
| Notes and range | EU dossier Kf range 0.2-3.6 mL/g, Kfoc range 89-340 mL/g, 1/n range 0.568-1.03, Soils=5 | |||
| pH sensitivity | No | |||
Key metabolites:
| Metabolite | Formation medium | Estimated maximum occurrence fraction | 1107/2009 relevancy |
|
| 5-amino-4-chloro-3(2H)-pyridazinone |
Soil | 0.559 | Major fraction, Relevant | |
| 5-amino-4-chloro-2-methyl-3(2H)-pyridazinone | Soil | - | Minor fraction, Not relevant | |
Other known metabolites:
| Metabolite name and reference | Aliases | Formation medium / Rate | Estimated maximum occurrence fraction | Metabolising enzymes |
| - | chloridazon metabolite A | Animal; Plant; Soil; Surface water | - | - |
| - | 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 (Urinary, 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 | - | - |
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Bio-concentration factor | BCF (l kg-1) | 12 | P4 | Low potential |
| CT50 (days) | Not available | - | ||
| Mammals - Acute oral LD50 (mg kg-1) | 2140 | A5 Rat | Low | |
| Mammals - Short term dietary NOEL | (mg kg-1) | 16 | L2 Rat, 2 year | High |
| (ppm diet) | - | - | ||
| Birds - Acute LD50 (mg kg-1) | > 2000 | A5 Colinus virginianus | Low | |
| Birds - Short term dietary (LC50/LD50) | > 1318 mg kg bw-1 day-1 | A5 Colinus virginianus | - | |
| Fish - Acute 96 hour LC50 (mg l-1) | 41.3 | A5 Oncorhynchus mykiss | Moderate | |
| Fish - Chronic 21 day NOEC (mg l-1) | 3.16 | A5 Oncorhynchus mykiss | Moderate | |
| Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) | 132.0 | A5 Daphnia magna | Low | |
| Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) | 6.23 | 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) | > 3.16 | A5 Lemna gibba | Moderate | |
| Non-target plants | - | - | - | |
| - | - | - | ||
| Algae - Acute 72 hour EC50, growth (mg l-1) | > 3.0 | A5 Pseudokirchneriella subcapitata | Moderate | |
| Algae - Chronic 96 hour NOEC, growth (mg l-1) | 0.73 | Q2 Unknown species | Moderate | |
| Honeybees (Apis spp.) | Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | > 200 | A5 | Low |
| Oral acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | > 200 | A5 | Low | |
| Unknown mode acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | - | - | - | |
| 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 | 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 | 3.2 | Mortality Dose: 0.26 Kg ha-1 A5 Typhlodromus pyri |
- | |
| Other arthropod (2) | LR50 g ha-1 | - | - | - |
| % Effect | 0.0 | Mortality Dose: 2.6 Kg ha-1 A5 Aphidius rhopalosiphi |
- | |
| Soil micro-organisms | Nitrogen mineralisation: No significant adverse effect Carbon mineralisation: No significant adverse effect |
A5 Dose: 26 mg kg-1 soil |
- | |
| Mesocosm study data | NOEAEC mg l-1 | - | - | - |
| NOEAEC mg l-1 | - | - | - | |
HUMAN HEALTH AND PROTECTION
for chloridazon
General:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Threshold of Toxicological Concern (Cramer Class) |
High (class III) | - | - | |
| Mammals - Acute oral LD50 (mg kg-1) | 2140 | A5 Rat | Low | |
| Mammals - Dermal LD50 (mg kg-1 body weight) | > 2000 | A5 Rat | - | |
| Mammals - Inhalation LC50 (mg l-1) | > 5.4 | A5 Rat, 4 hr | - | |
| Other Mammal toxicity endpoints | - | - | ||
| ADI - Acceptable Daily Intake (mg kg-1bw day-1) | 0.1 | A5 Rat, SF=100 | - | |
| ARfD - Acute Reference Dose (mg kg-1bw day-1) | None allocated | A5 | - | |
| AAOEL - Acute Acceptable Operator Exposure Level (mg kg-1 bw day-1) | - | - | - | |
| AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) | 0.2 | A5 Rat, SF=100 | - | |
| Dermal penetration studies (%) | 4 | A5 | - | |
| 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 | |||
| European MRLs | Click here for the EU MRL pesticide database | |||
| Drinking Water Standards | - | - | - | |
| Drinking Water MAC (μg l-1) | - | - | - | |
Health issues:
| Carcinogen | Genotoxic | Endocrine disrupter | Reproduction / development effects | Cholinesterase inhibitor | Neurotoxicant | |||
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A3; B3; C3; D0; E0 | - |
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| Respiratory tract irritant | Skin irritant | Skin sensitiser | Eye irritant | Phototoxicant | ||||
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| General human health issues | No further information available | |||||||
| Key: Genotoxicity A: Chromosome aberration (EFSA database) B: DNA damage/repair (EFSA database) C: Gene mutation (EFSA database) D: Genome mutation (EFSA database) E: Unspecified genotoxicity type (miscellaneous data source) 0: No data 1: Positive 2: Mixed/ambiguous results 3: Negative |
Key: Other : Yes, known to cause a problem  : No, known not to cause a problem  : Possibly, status not identified - : No data found |
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Handling issues:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
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| General |
Not explosive IMDG Transport Code is usually 9 |
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| CLP classification 2013 | Health: H317 Environment: H400, H410 |
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| EC Risk Classification |
Xn - Harmful: R43 N - Dangerous for the environment: R50, R53 |
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| EC Safety Classification |
S2, S24, S37, S60, S61 | |||
| WHO Classification | III | - | Slightly hazardous | |
| UN Number | Variable with product, usually 3077 or 3082 | |||
| Waste disposal & packaging |
Packaging Group III (minor danger) | |||
| Language | Name |
| English | chloridazon |
| French | chloridazone |
| German | Chloridazon |
| Danish | chloridazon |
| Italian | chloridazon |
| Spanish | cloridazon; pirazona |
| Greek | - |
| Slovenian | kloridazon |
| Polish | chlorydazon |
| Swedish | kloridazon |
| Hungarian | chloridazon |
| Dutch | chloridazon |
Record last updated: Tuesday 25 June 2019
Contact: aeru@herts.ac.uk