Difenzoquat metilsulfate (Ref: AC 84777)	Last updated: 22/08/2024
(Also known as: difenzoquat methyl sulphate; difenzoquat methyl sulfate; CL84777; BAS 450H; difenzoquat metilsulphate)

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SUMMARY

Difenzoquat metilsulfate is a herbicide mainly used to control wild oats. It is highly soluble in water and has a low volatility. It can be environmentally persistent depending on local conditions. It tends to be moderately toxic to biodiversity. Difenzoquat metilsulfate is also moderately toxic to mammals via the oral route.

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 High alert: Persistent; Potential for particle bound transport: High	Ecotoxicity Moderate alert: Daphnia acute ecotoxicity: Moderate; Bees acute contact ecotoxicity: Moderate; Earthworms acute ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate

GENERAL INFORMATION

Description	A post-emergence quarternary ammonium herbicide for wild oat control
Example pests controlled	Wild oats; Powdery mildew
Example applications	Cereals including wheat, barley; Alfalfa; Maize; Clover seed crops
Efficacy & activity	-
Availability status	Current
Introduction & key dates	1982, introduced USA

GB regulatory status

GB COPR regulatory status	Not approved
Date COPR inclusion expires	Expired
GB LERAP status	No UK approval for use as a pesticide

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status	Not approved
Dossier rapporteur/co-rapporteur	Not applicable
Date EC 1107/2009 inclusion expires	Expired
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
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	-

Chemical structure

Isomerism	None
Chemical formula	C₁₈H₂₀N₂O₄S
Canonical SMILES	CN1C(=CC(=[N+]1C)C2=CC=CC=C2)C3=CC=CC=C3.COS(=O)(=O)[O-]
Isomeric SMILES	-
International Chemical Identifier key (InChIKey)	XQEMNBNCQVQXMO-UHFFFAOYSA-M
International Chemical Identifier (InChI)	InChI=1S/C17H17N2.CH4O4S/c1-18-16(14-9-5-3-6-10-14)13-17(19(18)2)15-11-7-4-8-12-15;1-5-6(2,3)4/h3-13H,1-2H3;1H3,(H,2,3,4)/q+1;/p-1
2D structure diagram/image available?	Yes

General status

Pesticide type	Herbicide, Fungicide
Substance groups	Phenylpyrazole herbicide; Quarternary ammonium compound; Pyrazole herbicide
Minimum active substance purity	>96%
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Selective, absorbed by foliage. Acts via the rapid destruction of cell membranes.
CAS RN	43222-48-6
EC number	256-152-5
CIPAC number	367
US EPA chemical code	106401
PubChem CID	39424
CLP index number	No data found
Molecular mass	360.43
PIN (Preferred Identification Name)	1,2-dimethyl-3,5-diphenyl-1H-pyrazol-2-ium methyl sulfate
IUPAC name	1,2-dimethyl-3,5-diphenyl-1H-pyrazolium methyl sulfate
CAS name	1,2-dimethyl-3,5-diphenylpyrazolium methyl sulfate
Other status information	-
Relevant Environmental Water Quality Standards	-
Herbicide Resistance Class (HRAC MoA class)	Z
Herbicide Resistance Class (WSSA MoA class)	0
Insecticide Resistance Class (IRAC MoA class)	Not applicable
Fungicide Resistance Class (FRAC MOA class)	Not known
Examples of recorded resistance	-
Physical state	Colourless crystals
Related substances & organisms	difenzoquat

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Amvac Chemical Corp BASF King Tech American Cyanamid
Example products using this active	Finaven Yeh-Yan-Ku Avenge
Formulation and application details	Usually supplied as a water miscible liquid or soluble powder

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		765000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	High
Solubility - In organic solvents at 20 °C (mg l⁻¹)		360000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Dichloromethane	-
		500000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Chloroform	-
		558000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Methanol	-
		9800	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Acetone	-
Melting point (°C)		157	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		82	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source (open cup)	-
Octanol-water partition coefficient at pH 7, 20 °C	P	2.45 X 10-01	Calculated	-
	Log P	-0.61	T4 T = UN EPFA database. Dataset no longer available. 4 = Verified data	Low
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		0.8	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		7	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
		Weak acid
Vapour pressure at 20 °C (mPa)		0.01	H4 H = The US ARS pesticide properties database. Dataset is no longer available. 4 = Verified data	Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		5.70 X 10-11	H4 H = The US ARS pesticide properties database. Dataset is no longer available. 4 = Verified data	Non-volatile
Volatilisation as max % of applied dose lost	From plant surface	-	-	-
	From soil surface	-	-	-
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		-	-	-
Surface tension (mN m⁻¹)		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
General biodegradability		-
Soil degradation (days) (aerobic)	DT₅₀ (typical)	90	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Moderately persistent
	DT₅₀ (lab at 20 °C)	100	DW4 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. 4 = Verified data	Persistent
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	Other sources: DT₅₀ 3 months (R3)
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	-	-	-
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	Stable	W4 W = French database provided by ARVALIS-Institut du Végétal. Dataset no longer available. 4 = Verified data	Stable
	Note	-
Water-sediment DT₅₀ (days)		-	-	-
Water phase only DT₅₀ (days)		-	-	-
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)	-	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Non-mobile
	Koc (mL g⁻¹)	30000
	Notes and range	Other sources: Log Koc 4.49-5.80
Freundlich	Kf (mL g⁻¹)	166	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source (for difenzoquat)	Non-mobile
	Kfoc (mL g⁻¹)	9702
	1/n	1.39
	Notes and range	Kf range 29-664 mL g⁻¹; Kfoc range 1740-33200 mL g⁻¹; 1/n range 1.05-1.54; Soils=9
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		0.03	Calculated	Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	5.31 X 10-03	Calculated	-
	Note	-
Potential for particle bound transport index		High	Calculated	-
Potential for loss via drain flow		Non-mobile	Calculated	-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk		-	-	-
Bio-concentration factor	BCF (l kg⁻¹)	20	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
difenzoquat (Ref: BAS 450H)	Major fraction	-	-

Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		373	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	Moderate
Mammals - Short term dietary NOEL	(mg kg⁻¹)	-	L2 L = Pesticide manuals and hard copy reference books / other sources 2 = Unverified data of unknown source Rat 2 yr	-
	(ppm diet)	500		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		> 4640	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Colinus virginianus	Low
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		> 400	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	Moderate
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)		-	-	-
Soil micro-organisms		-	-	-
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)	36	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Apis mellifera	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)	-	-	-
	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)		-	-	-
Beneficial insects (Parasitic wasps)		-	-	-
Beneficial insects (Predatory mites)		-	-	-
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)		694	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Oncorhynchus mykiss	Low
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		2.63	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Daphnia magna	Moderate
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
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)		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		0.54	F1 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 1 = Estimated data with little or no verification Unknown species	Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	NOEAEC mg l⁻¹	-	-	-
Marine bivalves – Acute EC₅₀ development (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)		373	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		3540	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rabbit	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		0.36	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat 4 hr	-
Other Mammal toxicity endpoints		-	-	-
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)		-	-	-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)		-	-	-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)		-	-	-
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)		-	-	-
Dermal penetration studies (%)		-	-	-
Dangerous Substances Directive 76/464		-	-	-
Exposure Routes	Public	-
	Occupational	-
MRLs	European	EU MRL pesticide database
	Great Britain	GB MRL Register
	Notes	-
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 ; 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 No data found Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant XNo, known not to cause a problem XNo, known not to cause a problem XNo, known not to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser No data found XNo, known not to cause a problem No data found Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		Moderately toxic May cause irreversible eye damage

Handling issues

Property	Value and interpretation
General	Hygroscopic IMDG Transport Hazard Class 6.1
CLP classification 2013	Health: H302 Environment: H400, H410
WHO Classification	II (Moderately hazardous)
UN Number	UN2811
Waste disposal & packaging	Packaging Group II (moderate danger)
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	difenzoquat metilsulfate
French	-
German	-
Danish	-
Italian	-
Spanish	-
Greek	-
Polish	-
Swedish	-
Hungarian	-
Dutch	-
Norwegian	-

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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