Diphacinone	Last updated: 01/09/2023
(Also known as: diphacin; diphenadione)

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SUMMARY

Diphacinone is an anticoagulant rodenticide. It has a low aqueous solubility and a low volatility. It is not expected to be persistent in soils but may be in water systems depending on local conditions. Based on its physico-chemical properties, diphacinone is not expected to leach to groundwater. Ecotoxicological data is limited but diphacinone is moderately toxic to fish but less so to birds. This substance has a high mammalian oral toxicity and is an eye irritant.

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: Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate	Human health High alert: Mammals acute toxicity: High

GENERAL INFORMATION

Description	An anticoagulant rodenticide
Example pests controlled	Rats; Mice; Voles; Squirrels; Other small rodents
Example applications	Rats; Mice; Voles; Squirrels; Other small rodents
Efficacy & activity	-
Availability status	Current
Introduction & key dates	circa 1952

UK regulatory status

UK COPR regulatory status	Not approved
Date COPR inclusion expires	Expired
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	Not applicable
Date EC 1107/2009 inclusion expires	Expired
EU Candidate for substitution (CfS)	-
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, USA

Chemical structure

Isomerism	None
Chemical formula	C₂₃H₁₆O₃
Canonical SMILES	C1=CC=C(C=C1)C(C2=CC=CC=C2)C(=O)C3C(=O)C4=CC=CC=C4C3=O
Isomeric SMILES	No data
International Chemical Identifier key (InChIKey)	JYGLAHSAISAEAL-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C23H16O3/c24-21-17-13-7-8-14-18(17)22(25)20(21)23(26)19(15-9-3-1-4-10-15)16-11-5-2-6-12-16/h1-14,19-20H
2D structure diagram/image available?	Yes

General status

Pesticide type	Rodenticide
Substance groups	Indandione rodenticide
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Anti-coagulant with longer activity than warfarin
CAS RN	82-66-6
EC number	201-434-5
CIPAC number	131
US EPA chemical code	067701
PubChem CID	6719
CLP index number	606-038-00-X
Molecular mass	340.37
PIN (Preferred Identification Name)	2-(diphenylacetyl)-1H-indene-1,3(2H)-dione
IUPAC name	2-(diphenylacetyl)indan-1,3-dione
CAS name	2-(diphenylacetyl)-1H-indene-1,3(2H)-dione
Other status information	Marine Pollutant
Relevant Environmental Water Quality Standards	-
Herbicide Resistance Class (HRAC MoA class)	Not applicable
Herbicide Resistance Class (WSSA MoA class)	Not applicable
Insecticide Resistance Class (IRAC MoA class)	Not applicable
Fungicide Resistance Class (FRAC MOA class)	Not applicable
Examples of recorded resistance	-
Physical state	Pale yellow powder
Related substances & organisms	diphacinone sodium

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	velsicol Bell laboratories
Example products using this active	Ratindan Diphacine Ditrac Gold crest Kill-Ko Ramik
Formulation and application details	Available in a wide variety of formulations including meal, pellet, wax block, liquid bait and concentrate formulations.

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		0.3	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data	Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)		22900	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Acetone	-
		16800	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Ethanol	-
		1224	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Heptane	-
		43000	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Xylene	-
Melting point (°C)		146	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)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	7.08 X 1004	Calculated	-
	Log P	4.85	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	High
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		1.28	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		Not applicable	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
		Acidic
Vapour pressure at 20 °C (mPa)		1.37 X 10-05	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Low volatility
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		1.55 X 10-05	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Non-volatile
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)	5	S1 S = Expert judgement 1 = Estimated data with little or no verification	Non-persistent
	DT₅₀ (lab at 20 °C)	-	-	-
	DT₅₀ (field)	102	F3 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 ) 3 = Unverified data of known source	Persistent
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	Best available data - literature variable DT₅₀ 1-150 days
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	-	-	-
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	Stable	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data	Stable
	Note	-
Water-sediment DT₅₀ (days)		-	-	-
Water phase only DT₅₀ (days)		-	-	-

Soil adsorption and mobility

Property		Value	Source; quality score; and other information	Interpretation
Linear	Kd	-	S3 S = Expert judgement 3 = Unverified data of known source	Slightly mobile
	Koc	2255
	Notes and range	Other data source: 5477 mL g⁻¹ (US3)
Freundlich	Kf	-	-	-
	Kfoc	-
	1/n	-
	Notes and range	-
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		1.30	Calculated	Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	3.11 X 10-02	Calculated	-
	Note	-
Potential for particle bound transport index		High	Calculated	-
Potential for loss via drain flow		Slightly mobile	Calculated	-
Bio-concentration factor	BCF (l kg⁻¹)	-	-	-
	CT₅₀ (days)	-		-

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		2.3	F4 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 ) 4 = Verified data Rat	High
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	-
	(ppm diet)	0.1		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		> 3158	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Anas platyrhynchos	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)		-	-	-
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)	-	-	-
	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
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		2.8	F4 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 ) 4 = Verified data Oncorhynchus mykiss	Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		1.8	J4 J = Pesticide Action Network database (click here ) 4 = Verified data Daphnia magna	Moderate
Aquatic invertebrates - Chronic 21 day NOEC (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)		-	-	-
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
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)		2.3	F4 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 ) 4 = Verified data Rat	High
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		200	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		2.0	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
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 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 ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative No data found 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 XNo, known not to cause a problem 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		Highly toxic Anticoagulant

Handling issues

Property	Value and interpretation
General	IMDG Transport Hazard Class 6.1
CLP classification 2013	Health: H300, H372
WHO Classification	Ia (Extremely hazardous)
UN Number	UN2588
Waste disposal & packaging	-
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	diphacinone
French	diphacinone
German	Diphacinon
Danish	diphacinon
Italian	difacinone
Spanish	difacinone
Greek	diphacinone
Polish	difacynon
Swedish	-
Hungarian	-
Dutch	difacinon
Norwegian	-

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Record last updated:	01/09/2023
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