Dicofol (Ref: ENT 23648)	Last updated: 21/08/2024
(Also known as: kelthane; FW-293; decofol; DTMC)

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SUMMARY

Dicofol is an organochloride acaricide. It has a low aqueous solubility, volatile and, based on its chemical properties, is unlikely to leach to groundwater. It is moderately persistent in soils but does not normally persist in water. It is moderately toxic to mammals and has a high tendency to bioaccumulate. Dicofol is also an irritant and neurotoxin. It has a moderate toxicity to most biodiversity including honeybees and earthworms.

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: Potential for particle bound transport: High	Ecotoxicity High alert: Fish chronic ecotoxicity: High	Human health High alert: Endocrine disrupter; Neurotoxicant

GENERAL INFORMATION

Description	An acaricide used to control many species of phytophagous mite on a range of food and ornamental crops
Example pests controlled	Various mites including Pacific mite; two-spotted spider mite, tropical mites, tomato russet mite, citrus mite, European red mite
Example applications	Vegetables including beans, squash, peppers; Cotton; Cucumbers; Hops; Fruit including apples, pears, citrus, grapes
Efficacy & activity	-
Availability status	Current
Introduction & key dates	1956, first reported; 1957, first marketed 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	Spain
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	Isomeric - the o,p'-substituted isomer is chiral and may have enantiomer-specific activity but, the stereospecific activity of o,p'-dicofol has not been reported.
Chemical formula	C₁₄H₉Cl₅O
Canonical SMILES	C1=CC(=CC=C1C(C2=CC=C(C=C2)Cl)(C(Cl)(Cl)Cl)O)Cl
Isomeric SMILES	Clc1ccc(cc1)C(O)(c2ccc(Cl)cc2)C(Cl)(Cl)Cl
International Chemical Identifier key (InChIKey)	UOAMTSKGCBMZTC-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C14H9Cl5O/c15-11-5-1-9(2-6-11)13(20,14(17,18)19)10-3-7-12(16)8-4-10/h1-8,20H
2D structure diagram/image available?	Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
dicofol	-

General status

Pesticide type	Acaricide
Substance groups	Organochloride insecticide; Organochloride acaricide; Bridged diphenyl insecticide; Bridged diphenyl acaricide
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Non-systemic with contact action. CNS toxin.
CAS RN	115-32-2
EC number	204-082-0
CIPAC number	123
US EPA chemical code	10501
PubChem CID	8268
CLP index number	603-044-00-4
Molecular mass	370.49
PIN (Preferred Identification Name)	2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethan-1-ol
IUPAC name	2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol
CAS name	4-chloro-α-(4-chlorophenyl)-α-(trichloromethyl)benzenemethanol
Other status information	POP candidate; OSPAR pfa/soc; Chemical subject to PIC regulations
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)	UN
Fungicide Resistance Class (FRAC MOA class)	Not applicable
Examples of recorded resistance	Panonychus citri, Tetranychus arabicus, Tetranychus kanzawai, Tetranychus urticae, many others
Physical state	White crystals

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Agan Chemical Makhteshim-Agan Rohm & Hass Sedagri
Example products using this active	Carbax Mitigan Acarin Mitex kelthane Hilfol
Formulation and application details	Usually supplied as emulsifiable concentrates and wettable powders

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		0.8	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)		2600000	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Dichloromethane	-
		2750000	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Methanol	-
		1350000	C4 C = AGRITOX dataset. Dataset is no longer available. 4 = Verified data Xylene	-
		400000	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Acetone	-
Melting point (°C)		370.5	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	-
Boiling point (°C)		193	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		193	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	2.00 X 1004	Calculated	-
	Log P	4.3	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	High
Fat solubility of residues	Solubility	Soluble	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	-
	Data type	Regulatory data - observed in metabolism and farm animal feeding studies	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	-
Density (g ml⁻¹)		1.45	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		-	-	-
		-
Vapour pressure at 20 °C (mPa)		0.25	B5 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 5 = Verified data used for regulatory purposes	Low volatility. If applied directly to plants, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		2.45 X 10-02	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)	80	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Moderately persistent
	DT₅₀ (lab at 20 °C)	45	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	Moderately persistent
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	Best available data DT₅₀ range 40-80 days
Dissipation rate RL₅₀ (days) on plant matrix	Value	3.7	R4 R = Peer reviewed scientific publications 4 = Verified data	-
	Note	Published literature RL₅₀ range 1.7-5.9 days, 5 field & undercover grown crops, various matrices, n=6
Dissipation rate RL₅₀ (days) on and in plant matrix	Value	2.7	R4 R = Peer reviewed scientific publications 4 = Verified data	-
	Note	Published literature RL₅₀ range 2.6-2.8 days, 36 field crops, various matrices, n=3
Aqueous photolysis DT₅₀ (days) at pH 7	Value	26	K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source	Slow
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	3.3	K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source	Non-persistent
	Note	pH sensitive: DT₅₀ 85 days at pH 5, 26 minutes at pH 9 (L3)
Water-sediment DT₅₀ (days)		29	K2 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 2 = Unverified data of unknown source	Fast
Water phase only DT₅₀ (days)		-	-	-
Sediment 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)	-	H3 H = The US ARS pesticide properties database. Dataset is no longer available. 3 = Unverified data of known source	Non-mobile
	Koc (mL g⁻¹)	6064
	Notes and range	Other source: 6945 mL g⁻¹ sandy soil (H3); 5000 (G3)
Freundlich	Kf (mL g⁻¹)	-	-	-
	Kfoc (mL g⁻¹)	-
	1/n	-
	Notes and range	-
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		0.36	Calculated	Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	8.34 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)	10000	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 Whole fish	High potential
	CT₅₀ (days)	Not available		-

Known soil metabolites

Metabolite	Major/Minor fraction	Estimated maximum occurrence fraction	Notes
2-chlorobenzoic acid (Ref: AE-C500233)	-	-	-
1-(2-chlorophenyl)-1-(4'-chlorophenyl)-2,2-dichloroethanol	-	-	Aerobic
o,p-dichlorobenzohydrol (Ref: o,p-DCBH)	-	-	Aerobic
3-hydroxy-2,4-dichlorobenzophenone (Ref: OH-DCBP)	-	-	Aerobic
3-hydroxy-4,4'-dichlorobenzophenone (Ref: 3-OH-DCBP)	-	-	Aerobic
1-(2-chlorophenyl)-1-(4'-chlorophenyl)-2,2-dichloroethanol (Ref: FW-152)	-	-	Aerobic
1,1-bis(4-chlorophenyl)-2,2-dichloroethanole	-	-	Anaerobic
2,4-dichlorobenzophenone	-	-	Photolysis
2,4-dichlorobenzhydrol	-	-	Aerobic

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)		578	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)	0.25	L2 L = Pesticide manuals and hard copy reference books / other sources 2 = Unverified data of unknown source Rat 2 yr	High
	(ppm diet)	5		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		1418	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Coturnix japonica	Moderate
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		43.1	L3 L = Pesticide manuals and hard copy reference books / other 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)	19	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 Apis mellifera	Moderate
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	> 10	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 Apis mellifera	Moderate
	Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	Chronic	-	-	-
	Notes	-
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)		Moderately harmful	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source Parasitic wasp	-
Beneficial insects (Predatory mites)		Harmful	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source Predatory mite	-
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)		0.51	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Lepomis macrochirus	Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)		0.0044	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Oncorhynchus mykiss	High
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		3.83	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 Danio rerio EC₅₀ Embryo	Moderate
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		0.14	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)		125	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source Daphnia magna	Low
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)		630	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Chironomus dilutus Growth	Low
Aquatic plants (free-floating, growth) - Acute 7 day EC₅₀, biomass (mg l⁻¹)		-	-	-
Aquatic plants (rooted, growth) - Acute 14 day EC₅₀, biomass (mg l⁻¹)		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		0.075	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Scenedesmus subspicatus	Moderate
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		0.05	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	-	-	-
Marine bivalves		-	-	-

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)		578	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)		2500	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rabbit	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		5.0	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)		0.002	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)		0.15	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)		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	-
Dermal penetration studies (%)		-	-	-
Dangerous Substances Directive 76/464		List I; List II	-	-
Exposure Routes	Public	Low risk to Europeans as no longer approved for use
	Occupational	Low risk to Europeans as no longer approved for use
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 ?Possibly, status not identified 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 ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative ✓Yes, known to cause a problem Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant No data found XNo, known not to cause a problem ✓Yes, known to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser ✓Yes, known 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		Harmful by inhalation, ingestion and through skin contact IARC Group 3 carcinogen - not classifiable; US EPA - possible human carcinogen Endocrine issues - Inhibition of androgen synthesis

Handling issues

Property	Value and interpretation
General	No information available
CLP classification 2013	Health: H302, H312, H315, H317 Environment: H400, H410
WHO Classification	II (Moderately hazardous)
UN Number	-
Waste disposal & packaging	-
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	dicofol
French	dicofol
German	Dicofol
Danish	dicofol
Italian	dicofol
Spanish	dicofol
Greek	dicofol
Polish	dikofol
Swedish	-
Hungarian	-
Dutch	dicofol
Norwegian	-

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Record last updated:	21/08/2024
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