Prothoate (Ref: EI 18682)

Prothoate (Ref: EI 18682)	Last updated: 26/05/2025
(Also known as: trimethoate; oleofac)

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 Moderate alert: Drainflow: Moderately mobile Warning: Significant data are missing	Ecotoxicity High alert: Birds acute ecotoxicity: High Warning: Significant data are missing	Human health High alert: Mammals acute toxicity: High; Acetyl cholinesterase inhibitor; Neurotoxicant

GENERAL INFORMATION

Description

An obsolete aliphatic insecticide and acaricide

Example pests controlled

Aphids; Spider mites; Psyllids; Lace bugs; Thrips

Example applications

Fruit including fruit trees, citrus; Vegetables; Cotton; Ornamentals

Efficacy & activity

Availability status

Considered obsolete but may be available in some countries

Introduction & key dates

1955, first reported

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

Chemical structure

Isomerism

None

Chemical formula

C₉H₂₀NO₃PS₂

Canonical SMILES

CCOP(=S)(OCC)SCC(=O)NC(C)C

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

QTXHFDHVLBDJIO-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C9H20NO3PS2/c1-5-12-14(15,13-6-2)16-7-9(11)10-8(3)4/h8H,5-7H2,1-4H3,(H,10,11)

2D structure diagram/image available?

Yes

General status

Pesticide type

Insecticide; Acaricide

Substance groups

Organophosphate insecticide; Organophosphate acaricide; Organothiophosphate insecticide; Organothiophosphate acaricide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Acetylcholinesterase (AChE) inhibitor.

CAS RN

2275-18-5

EC number

218-893-2

CIPAC number

None allocated

US EPA chemical code

344300

PubChem CID

16774

CLP index number

015-032-00-0

Molecular mass

285.36

PIN (Preferred Identification Name)

IUPAC name

2-diethoxyphosphinothioylthio-N-isopropylacetamide

CAS name

O,O-diethyl S-[2-[(1-methylethyl)amino]-2-oxoethyl] phosphorodithioate

Other status information

Marine Pollutant

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)

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Myzus persicae, Phorodon humuli, Tetranychus urticae

Physical state

Colourless sand-like solid

Formulations

Property

Value

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

Cyanamid
Agrimont
Schering
Farmoplant

Example products using this active

Fac
Erysit Super
Fac Super

Formulation and application details

Usually 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)

2500

at 25 °C

High

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

Miscible

Hexane

Miscible

Cyclohexane

Melting point (°C)

28.5

Boiling point (°C)

Degradation point (°C)

Flashpoint (°C)

160

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

1.48 X 10⁰²

Calculated

Log P

2.17

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.15

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

at 25 °C

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)

6.64 X 10^-06

at 25 °C

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)

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

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

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

Value

Stable

Note

Water-sediment DT₅₀ (days)

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

K_d (mL g⁻¹)

Moderately mobile

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

K_foc (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

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)

Low risk

Based on LogP < 3

Low risk

CT₅₀ (days)

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

> 8

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)

55.95

median across 2 species

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)

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)

> 20

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)

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 (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)

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

Mesocosm study data

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)

> 8

Rat

High

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

655

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

0.003

Rat 4 hr

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

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

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Highly toxic
Small doses at frequent intervals are additive

Handling issues

Property

Value and interpretation

General

IMDG Transport Hazard Class 6.1
Container may explode in fire
Not compatible with alkaline substances

CLP classification 2013

Health: H300, H310
Environment: H412

WHO Classification

Not classified: Obsolete (Not classified: Obsolete)

UN Number

UN3018

Waste disposal & packaging

Packaging Group I (great danger)

Shelf-life, storage, stability and reactivity

Stable and non-reactive under normal conditions of use, storage and transport.

TRANSLATIONS

Language

Name

English

prothoate

French

prothoate

German

Prothoat

Danish

prothoat

Italian

protoato

Spanish

protioate

Greek

prothoate

Polish

protoat

Swedish

Hungarian

Dutch

prothoaat

Norwegian

Record last updated:	26/05/2025
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