Omethoate (Ref: ENT 25776)	Last updated: 21/08/2024
(Also known as: dimethoate-met; dimethoxon)

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SUMMARY

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: Drainflow: Mobile	Ecotoxicity High alert: Birds acute ecotoxicity: High; Daphnia acute ecotoxicity: High; Daphnia chronic ecotoxicity: High; Bees acute oral ecotoxicity: High	Human health High alert: Mammals acute toxicity: High; Endocrine disrupter; Acetyl cholinesterase inhibitor; Neurotoxicant

GENERAL INFORMATION

Description	An insecticide and acaricide to control a wide range of pests on fruit, hops and other crops. Also a pesticide transformation product
Example pests controlled	Aphids; Mites; Caterpillars; Beetles; Mealybugs; Scale
Example applications	Fruit including citrus, apples, plum; Hops; Sugarbeet; Potatoes; Cereals; Ornamentals
Efficacy & activity	-
Availability status	Current
Introduction & key dates	circa 1960, introduced

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)	-
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

Chemical structure

Isomerism	None
Chemical formula	C₅H₁₂NO₄PS
Canonical SMILES	CNC(=O)CSP(=O)(OC)OC
Isomeric SMILES	No data
International Chemical Identifier key (InChIKey)	PZXOQEXFMJCDPG-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C5H12NO4PS/c1-6-5(7)4-12-11(8,9-2)10-3/h4H2,1-3H3,(H,6,7)
2D structure diagram/image available?	Yes

General status

Pesticide type	Insecticide, Acaricide, Metabolite
Metabolite Type	Soil, Groundwater, Surface water, Sediment, Air
Substance groups	Organophosphate insecticide; Organophosphate acaricide; Organothiophosphate insecticide; Organothiophosphate acaricide
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Systemic with contact and stomach action. Acetylcholinesterase (AchE) inhibitor.
CAS RN	1113-02-6
EC number	214-197-8
CIPAC number	202
US EPA chemical code	-
PubChem CID	14210
CLP index number	015-066-00-6
Molecular mass	213.2
PIN (Preferred Identification Name)	-
IUPAC name	2-dimethoxyphosphinoylthio-N-methylacetamide
CAS name	O,O-dimethyl S-(2-(methylamino)-2-oxoethyl) phosphorothioate
Other status information	Chemical subject to PIC regulations; Subject to the provisions of the UK Poisons Act 1972
Relevant Environmental Water Quality Standards	UK Statutory standard for the protection of aquatic life in surface waters: 0.01 µg l⁻¹
Herbicide Resistance Class (HRAC MoA class)	Not applicable
Herbicide Resistance Class (WSSA MoA class)	Not applicable
Insecticide Resistance Class (IRAC MoA class)	1B
Fungicide Resistance Class (FRAC MOA class)	Not applicable
Examples of recorded resistance	Leptinotarsa decemlineata, Aonidella aurantii, Aphis gossypii, Macrosiphum avenae, Myzus persicae, many others
Physical state	Colourless liquid

Can be a metabolite of:

Parent	Formation medium	Estimated maximum occurrence fraction	1107/2009 relevancy
dimethoate	Soil	0.154	Major fraction

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Bayer CropScience King Tech Corp.
Example products using this active	Le-ma 290 SL Atease Modern Folimat
Formulation and application details	Usually supplied as a soluble concentrate or emulsifiable concentrate

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		500000	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	High
Solubility - In organic solvents at 20 °C (mg l⁻¹)		Miscible	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Acetone	-
		Miscible	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Methanol	-
Melting point (°C)		-28	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Solidifies	-
Boiling point (°C)		135	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		128	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
Octanol-water partition coefficient at pH 7, 20 °C	P	1.26 X 10-01	Calculated	-
	Log P	-0.9	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	Low
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		1.32	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	-
Dissociation constant pKa) at 25 °C		-	-	-
		-
Vapour pressure at 20 °C (mPa)		19.0	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	Highly volatile. If applied directly to plants or soil, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		4.62 X 10-09	V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source	Non-volatile
Volatilisation as max % of applied dose lost	From plant surface	-	-	-
	From soil surface	-	-	-
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		Neutral soln: 194.4nm=6366.1 Acid soln: 207.5nm=2401.2 Basic soln: 233.5nm=3020.7	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	-
Surface tension (mN m⁻¹)		-	-	-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
General biodegradability		-
Soil degradation (days) (aerobic)	DT₅₀ (typical)	0.1	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	Non-persistent
	DT₅₀ (lab at 20 °C)	0.1	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	Non-persistent
	DT₅₀ (field)	14	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	Non-persistent
	DT₉₀ (lab at 20 °C)	0.6	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	Non-persistent
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	EU 2017 dossier Lab studies Dt50 range 0.1-0.3 days, DT₉₀ range 0.1-1.2 days, Soils=3
Dissipation rate RL₅₀ (days) on plant matrix	Value	-	-	-
	Note	-
Dissipation rate RL₅₀ (days) on and in plant matrix	Value	1.7	R4 R = Peer reviewed scientific publications 4 = Verified data	-
	Note	Published literature RL₅₀ range 1.3-2.1 days, wheat, various matrices, n=3
Aqueous photolysis DT₅₀ (days) at pH 7	Value	Stable	B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 4 = Verified data	Stable
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	17	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	Non-persistent
	Note	-
Water-sediment DT₅₀ (days)		4.5	K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data	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)	0.53	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	Mobile
	Koc (mL g⁻¹)	41.3
	Notes and range	EU dossier Kd range 0.20-0.99 mL g⁻¹, Koc range16-87 mL g⁻¹, Soils=3
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		2.73	Calculated	Transition state
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	1.17 X 10-01	Calculated	-
	Note	-
Potential for particle bound transport index		Low	Calculated	-
Potential for loss via drain flow		Mobile	Calculated	-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk		4.9	A4 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 ) 4 = Verified data Calculated using the Atkinson method. Assumed 1.6E+05 OH/cm³, 12 hr	Below the level of concern for long-range air transport
Bio-concentration factor	BCF (l kg⁻¹)	75	Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source Estimated	Low potential
	CT₅₀ (days)	Not available		-

Known soil and groundwater metabolites

None

Other known metabolites

Metabolite name and reference	Aliases	Formation medium / Rate	Estimated maximum occurrence fraction
dimethylthiophosphate	DMTP	Mammal	-
dimethylphosphate	DMP	Mammal	-

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		50.0	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)	-	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 Rat	-
	(ppm diet)	0.5		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		9.9	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 Colinus virginianus	High
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		46	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 Eisenia andrei	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)	-	-	-
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	0.048	B4 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 4 = Verified data Apis mellifera	High
	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)		-	-	-
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)		9.1	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 Oncorhynchus mykiss	Moderate
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)		0.022	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 Daphnia magna	High
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		0.000004	P3 P = Other non-EU, UK or US Governments and Regulators 3 = Unverified data of known source Unknown species	High
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)		167.5	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 Scenedesmus subspicatus	Low
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		-	-	-
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)		50.0	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)		145.0	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		0.3	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		List I; List II	-	-
Exposure Routes	Public	-
	Occupational	Occupational exposure may occur through inhalation and dermal contact
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 ; D2 D = Genome mutation (EFSA database) 2 = Mixed/ambiguous results ; C2 C = Gene mutation (EFSA database) 2 = Mixed/ambiguous results ; D0 D = Genome mutation (EFSA database) 0 = No data ; E0 E = Unspecified genotoxicity type (miscellaneous data source) 0 = No data ✓Yes, known to cause a problem Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant XNo, known not to cause a problem ✓Yes, known to cause a problem ✓Yes, known to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser No data found ✓Yes, known to cause a problem ✓Yes, known to cause a problem Eye irritant Phototoxicant   XNo, known not to cause a problem No data found
General human health issues		Toxic if swallowed May cause cyanosis

Handling issues

Property	Value and interpretation
General	Flammable IMDG Transport Hazard Class 6.1
CLP classification 2013	Health: H301, H312 Environment: H400
WHO Classification	Ib (Highly hazardous)
UN Number	UN3018
Waste disposal & packaging	-
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	omethoate
French	omethoate
German	Omethoat
Danish	omethoate
Italian	ometoato
Spanish	ometoato
Greek	-
Polish	ometoat
Swedish	-
Hungarian	-
Dutch	-
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