Demeton (Ref: ENT 17295)

Demeton (Ref: ENT 17295)	Last updated: 10/09/2023
(Also known as: E 1059; mercaptophos)

SUMMARY

Demeton is an organophosphate insecticide. It has a high aqueous solubility and is highly volatile. There are considerable gaps in literature regarding its environmental fate. Demeton is highly toxic to mammals, is a neurotoxin and may adversely affect reproduction and/or development. It is also an acetyl cholinesterase inhibitor. It is highly toxic to birds and aquatic invertebrates. It moderately toxic to fish and honeybees.

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
	Ecotoxicity High alert: Birds acute ecotoxicity: High; Daphnia acute ecotoxicity: High	Human health High alert: Mammals acute toxicity: High; Reproduction/development effects; Acetyl cholinesterase inhibitor; Neurotoxicant

GENERAL INFORMATION

Description

An insecticide used to control sucking insects on a range of crops

Example pests controlled

Aphids; Sawflies; Spidermites; Thrips

Example applications

Fruit; Vegetables; Potatoes; Cereals; Ornamentals; Tree nuts

Efficacy & activity

Availability status

Considered obsolete but may be available in some countries

Introduction & key dates

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

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

Demeton is a mixture of thiol and thiono isomers

Chemical formula

C₈H₁₉O₃PS₂

Canonical SMILES

CCOP(=S)(OCC)OCCSCC

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

DGLIBALSRMUQDD-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/2C8H19O3PS2/c1-4-10-12(9,11-5-2)14-8-7-13-6-3;1-4-9-12(13,10-5-2)11-7-8-14-6-3/h2*4-8H2,1-3H3

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

8065-48-3

EC number

620-378-6

CIPAC number

None allocated

US EPA chemical code

057601

PubChem CID

24722

CLP index number

No data found

Molecular mass

258.34

PIN (Preferred Identification Name)

reaction mixture of O,O-diethyl O-[2-(ethylsulfanyl)ethyl] phosphorothioate and O,O-diethyl S-[2-(ethylsulfanyl)ethyl] phosphorothioate

IUPAC name

reaction mixture of O,O-diethyl O-2-ethylthioethyl phosphorothioate and O,O-diethyl S-2-ethylthioethyl phosphorothioate

CAS name

O,O-diethyl O-(2-(ethylthio)ethyl) phosphorothioate mixture with O,O-diethyl S-(2-(ethylthio)ethyl) phosphorothioate

Other status information

Relevant Environmental Water Quality Standards

UK Statutory standard for the protection of aquatic life in inland, coastal and territorial waters: 0.5 µg l⁻¹ as annual average

Herbicide Resistance Class (HRAC MoA class)

Not applicable

Herbicide Resistance Class (WSSA MoA class)

Not applicable

Insecticide Resistance Class (IRAC MoA class)

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Aphis fabae, Myzus persicae, Tetranychus urticae, Tetranychus viennensis, Aphis gossypii, Liriomyza trifolii, many others

Physical state

Bright yellow oil

Related substances & organisms

demeton-O-methyl

demeton-O-methyl sulfone

demeton-S-methyl

demeton-S-methyl sulfone

Formulations

Property

Value

Example manufacturers & suppliers of products using this active now or historically

Bayer
Mobay

Example products using this active

Demox
Systemox
Systox

Formulation and application details

Formulated as an emulsifiable concentrate.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

666

(varies significantly with isomer)

High

Solubility - In organic solvents at 20 °C (mg l⁻¹)

Melting point (°C)

-25

Boiling point (°C)

125

Degradation point (°C)

Flashpoint (°C)

Octanol-water partition coefficient at pH 7, 20 °C

1.62 X 10⁰³

Calculated

Log P

3.21

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.126

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

36.26

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)

0.387

Moderately 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)

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

Dissipation rate RL₅₀ (days) on plant matrix

Value

7.8

Note

Published literature RL₅₀ range 3.9-11.5 days, leaves of 6 field crops, n=5

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

11.7

Note

Published literature RL₅₀ range 4.8-30.0 days, various matrices from of 6 field crops, n=6

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7

Value

Note

Water-sediment DT₅₀ (days)

Water 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.

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

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

SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate

Value

Cannot be calculated

Note

Potential for particle bound transport index

Potential for loss via drain flow

Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk

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)

2.5

Rat

High

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

7.18

Anas platyrhynchos

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)

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)

> 2.6

Moderate

Chronic

Bumblebees (Bombus spp.)

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

> 1.0

Bombus lucorum 24 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 bee species (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 bee species (2)

Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)

0.026

Nomia melanderi

High

Mode of exposure

Contact

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)

1.6

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)

0.0104

Daphnia pulex

High

Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)

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)

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

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)

2.5

Rat

High

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

8.2

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

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

May be absorbed from the gastrointestinal tract, skin, and by inhalation

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

No data found

; ; ; ;

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

No information available

CLP classification 2013

Health: H300, H310

WHO Classification

Not classified: Obsolete (Not classified: Obsolete)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

demeton

French

demeton

German

Demeton

Danish

demeton

Italian

demeton

Spanish

demeton

Greek

demeton

Polish

demeton

Swedish

demeton

Hungarian

demeton

Dutch

demeton

Norwegian

Record last updated:	10/09/2023
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