Demeton-S-methyl

Demeton-S-methyl	Last updated: 21/05/2022
(Also known as: methyl-mercaptophos-teolovy; methyl demeton; mercapthphos)

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 groups

Organophosphate insecticide; Organothiophosphate insecticide; Organophosphate acaricide; 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

919-86-8

EC number

213-052-6

CIPAC number

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)

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

Related substances & organisms

demeton

demeton-O-methyl

demeton-O-methyl sulfone

demeton-S-methyl sulfone

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

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

2.09 X 10⁰¹

Calculated

Log P

1.32

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.21

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

Highly volatile

Henry's law constant at 25 °C (Pa m³ mol⁻¹)

4.19 X 10^-04

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

Non-persistent

DT₅₀ (lab at 20 °C)

2.7

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

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

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

K_d

Moderately mobile

K_oc

Notes and range

Freundlich

K_f

K_foc

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

Bio-concentration factor

BCF (l kg⁻¹)

0.5

Based on LogP < 3

Low potential

CT₅₀ (days)

Not available

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

demeton-S-methyl sulfone

Animal

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

Rat

High

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 year

(ppm diet)

Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)

Birds - Acute LD₅₀ (mg kg⁻¹)

Coturnix japonica

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)

> 250

Eisenia foetida

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)

2.6

Apis mellifera 24hr

Moderate

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

> 0.19

Apis mellifera

High

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)

> 2.68

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

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

Beneficial insects (Ladybirds)

Beneficial insects (Lacewings)

Beneficial insects (Parasitic wasps)

Beneficial insects (Predatory mites)

Harmless

Typhlodromus pyri

Beneficial insects (Ground beetles)

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 6.4

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)

> 0.023

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)

Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)

22.1

Scenedemus subspicatus

Low

Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)

Unknown species

Low

Mesocosm study data

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)

Rat

High

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

0.13

Rat (aerosol)

Other Mammal toxicity endpoints

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

0.0003

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)

Mammalian dose elimination route and rate

Rapidly eliminated in urine

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

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

WHO Classification

Ib (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

Record last updated:	21/05/2022
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