chloridazon (Ref: BAS 119H) ** pyrazon ** pyrazone ** PAC ** chloridazone ** Translations

---

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

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	chlorpropham metamitron ethofumesate lenacil propachlor quinmerac

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
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	-	-

ECOTOXICOLOGY
for chloridazon

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	Contact acute 48 hour LD50 (μg bee-1)	> 200	A5	Low
	Oral acute 48 hour LD50 (μg bee-1)	> 200	A5	Low
	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	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 Limits		-	-	-
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	Mutagen	Endocrine disrupter	Reproduction / development effects	Cholinesterase inhibitor	Neurotoxicant
	-	-
Respiratory tract irritant	Skin irritant	Skin sensitiser	Eye irritant	Phototoxicant
				-
General human health issues		No further information available

: 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 IMDG Transport Code is usually 9
CLP classification 2013		Health: H317 Environment: H400, H410
EC Risk Classification		Xn - Harmful: R43 N - Dangerous for the environment: R50, R53
EC Safety Classification		S2, S24, S37, S60, S61
WHO Classification		III	-	Slightly hazardous
US EPA Classification (formulation)		III	-	Caution - Slightly toxic
UN Number		Variable with product, usually 3077 or 3082
Waste disposal & packaging		Packaging Group III (minor danger)

TRANSLATIONS
for chloridazon

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: Wednesday 03 April 2019
Contact: aeru@herts.ac.uk