Demeton-S-methyl	Last updated: 18/08/2021
(Also known as: methyl-mercaptophos-teolovy; methyl demeton; mercapthphos)

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SUMMARY

Demeton-S-methyl is an insecticide and acaricide. It is highly soluble in water, volatile and, based on its physico-chemical data, it is not expected to leach to groundwater. It is not persistent in soil systems. Demeton-S-methyl is highly toxic to mammals, a cholinesterase inhibitor, a neurotoxin and a recognised irritant. It is highly toxic to birds, aquatic invertebrates and honey bees and moderately toxic to most other species including fish 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 Moderate alert: Drainflow: Moderately mobile	Ecotoxicity High alert: Birds acute ecotoxicity: High; Daphnia acute ecotoxicity: High; Bees acute oral ecotoxicity: High	Human health High alert: Mammals acute toxicity: High; Acetyl cholinesterase inhibitor; Neurotoxicant

GENERAL INFORMATION

Description	An insecticide used to control aphids and other sucking insects on a range of crops
Example pests controlled	Aphids including woolly aphids, citrus aphids, Russian aphids; Sawflies; Bryobia mites; Lacebugs
Example applications	Vegetables including beans, peas, brassicas, peppers, aubergines, onions; Fruit including olives, peaches, plums, apricots; Tomatoes; Cotton; Peanuts; Wheat; Maize; Sorghum
Efficacy & activity	-
Availability status	-
Introduction & key dates	1957

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)	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

Additional information

Also used in	-

Chemical structure

Isomerism	The methyl ester of the S-form of isomeric demeton
Chemical formula	C₆H₁₅O₃PS₂
Canonical SMILES	CCSCCSP(=O)(OC)OC
Isomeric SMILES	No data
International Chemical Identifier key (InChIKey)	WEBQKRLKWNIYKK-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/C6H15O3PS2/c1-4-11-5-6-12-10(7,8-2)9-3/h4-6H2,1-3H3
2D structure diagram/image available?	Yes

General status

Pesticide type	Insecticide, Acaricide
Substance group	Organophosphate
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Synthetic
Mode of action	Systemic with contact and stomach action. Acetylcholinesterase (AChE) inhibitor.
CAS RN	919-86-8
EC number	213-052-6
CIPAC number	47
US EPA chemical code	-
PubChem CID	13526
Molecular mass	230.29
PIN (Preferred Identification Name)	S-[2-(ethylsulfanyl)ethyl] O,O-dimethyl phosphorothioate
IUPAC name	S-2-ethylthioethyl O,O-dimethyl phosphorothioate
CAS name	S-(2-(ethylthio)ethyl) O,O-dimethyl phosphorothioate
Other status information	PAN Bad Actor Chemical; Subject to the provisions of the UK Poisons Act 1972
Relevant Environmental Water Quality Standards	-
Herbicide Resistance Classification (HRAC)	Not applicable
Herbicide Resistance Classification (WSSA)	Not applicable
Insecticide Resistance Classification (IRAC)	1B
Fungicide Resistance Classification (FRAC)	Not applicable
Examples of recorded resistance	Aphis gossypii, Panonychus ulmi, Tetranychus urticae, Tetranychus viennensis, Aculus cornutus, Aphis craccivora, many others
Physical state	Yellow oil

Formulations

Property	Value
Example manufacturers & suppliers of products using this active now or historically	Bayer CropScience Doo Yang Industrial Co. Ltd.
Example products using this active	Metasystox Duratox DSM Demeton EC
Formulation and application details	Usually supplied as an emulsifiable concentrate.

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		22000	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)		-	-	-
Melting point (°C)		-	-	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	2.09 X 1001	Calculated	-
	Log P	1.32	G4 G = Extension Toxicology network database EXTOXNET (click here ) 4 = Verified data	Low
Bulk density (g ml⁻¹)		1.21	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)		40	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Highly volatile
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		4.19 X 10-04	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)	2.7	K4 K = Research datasets, e.g. Pandora, Demetra 4 = Verified data	Non-persistent
	DT₅₀ (lab at 20 °C)	2.7	K4 K = Research datasets, e.g. Pandora, Demetra 4 = Verified data	Non-persistent
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	DT₅₀ modelling endpoint	-	-	-
	Note	-
Dissipation rate RL₅₀ on plant matrix	Value	-	-	-
	Note	-
Dissipation rate RL₅₀ on and in plant matrix	Value	3.0	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source	-
	Note	Mango fruit, n=1
Aqueous photolysis DT₅₀ (days) at pH 7	Value	-	-	-
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	56	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	Moderately persistent
	Note	pH sensitive: DT₅₀ 63 days at pH 4, 8 days at pH 9 all at 22 °C
Water-sediment DT₅₀ (days)		-	-	-
Water phase only DT₅₀ (days)		-	-	-

Soil adsorption and mobility

Property		Value	Source; quality score; and other information	Interpretation
Linear	Kd	-	W3 W = French database provided by ARVALIS-Institut du Végétal 3 = Unverified data of known source	Moderately mobile
	Koc	90
	Notes and range	-
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		0.88	Calculated	Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate	Value	1.95 X 10-03	Calculated	-
	Note	-
Potential for particle bound transport index		Low	Calculated	-
Potential for loss via drain flow		Moderately mobile	Calculated	-

Key metabolites

Metabolite	Formation medium	Estimated maximum occurrence fraction	1107/2009 relevancy
demeton-S-methyl sulfone	Animal	-	-

ECOTOXICOLOGY

Property		Value	Source; quality score; and other information	Interpretation
Bio-concentration factor	BCF (l kg⁻¹)	0.5	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source (LogP < 3)	Low potential
	CT₅₀ (days)	Not available		-
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		40	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (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 2 year	-
	(ppm diet)	1		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		44	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Coturnix japonica	High
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		> 6.4	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Oncorhynchus mykiss	Moderate
Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		> 0.023	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Daphnia magna	High
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)		-	-	-
Non-target plants		-	-	-
		-	-	-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)		22.1	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Scenedemus subspicatus	Low
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)		10	Q2 Q = Miscellaneous internet resources 2 = Unverified data of unknown source Unknown species	Low
Honeybees (Apis spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	2.6	F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment ) 3 = Unverified data of known source Apis mellifera 24hr	Moderate
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	> 0.19	K4 K = Research datasets, e.g. Pandora, Demetra 4 = Verified data Apis mellifera	High
	Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
Bumblebees (Bombus spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	> 2.68	R4 R = Peer reviewed scientific publications 4 = Verified data Bombus terrestris 48 hr	Moderate
		-
	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 pollinators (1)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	0.076	R4 R = Peer reviewed scientific publications 4 = Verified data Megachile rotundata	High
	Mode of exposure	Contact
Other pollinators (2)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	-	-	-
	Mode of exposure	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		> 250	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Eisenia foetida	Moderate
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)		-	-	-
Other soil macro-organisms	Acute LC₅₀ (mg kg⁻¹)	-	-	-
	Chronic NOEC (mg kg⁻¹)	-	-	-
Other arthropod (1)	LR₅₀ g ha⁻¹	-	-	-
	% Effect	Harmless	AB1 AB = SELECTV Database 1 = Estimated data with little or no verification Typhlodromus pyri	-
Other arthropod (2)	LR₅₀ g ha⁻¹	-	-	-
	% Effect	-	-	-
Soil micro-organisms		-	-	-
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)		40	F4 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents (US EPA Databases Related to Pesticide Risk Assessment ) 4 = Verified data Rat	High
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		30	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		0.13	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source Rat (aerosol)	-
Other Mammal toxicity endpoints		-	-	-
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)		0.0003	L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source	-
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	-
MRLs	European	EU MRL pesticide database
	Great Britain	GB MRL Register
	Notes	-
Drinking Water Standards		-	-	-
Drinking Water MAC (μg l⁻¹)		-	-	-

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 ; E1 E = Unspecified genotoxicity type (miscellaneous data source) 1 = Positive XNo, known not to cause a problem Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant ?Possibly, status not identified ✓Yes, known to cause a problem ✓Yes, known to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser ?Possibly, status not identified ✓Yes, known to cause a problem No data found Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		No further information available

Handling issues

Property	Value and interpretation
General	Combustible
CLP classification 2013	Health: H301, H311 Environment: H411
EC Risk Classification	T - Toxic: R24/25 N - Dangerous for the environment: R51, R53
EC Safety Classification	S1/2, S28, S36/37, S45, S61
WHO Classification	Ib (Highly hazardous / Highly hazardous)
UN Number	Usually 3018
Waste disposal & packaging	-

TRANSLATIONS

Language	Name
English	demeton-S-methyl
French	demeton-S-methyle
German	Demeton-S-methyl
Danish	demeton-S-methyl
Italian	demeton-s-metil
Spanish	demeton-S-metil
Greek	demeton-S-methyl
Polish	demeton-S-metylowy
Swedish	-
Hungarian	-
Dutch	demeton-S-methyl

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Record last updated:	18/08/2021
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