Pirimiphos-methyl (Ref: OMS 1424)

Pirimiphos-methyl (Ref: OMS 1424)	Last updated: 20/05/2025
(Also known as: pyrimiphos-méthyl; PP 511)

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: Moderately persistent; Drainflow: Slightly mobile; Potential for particle bound transport: Medium	Ecotoxicity High alert: Daphnia acute ecotoxicity: High; Daphnia chronic ecotoxicity: High; Bees acute contact ecotoxicity: High; Bees acute oral ecotoxicity: High	Human health High alert: Acetyl cholinesterase inhibitor

GENERAL INFORMATION

Description

An organophosphate fumigant insecticide used to control a wide range of insects and mites

Example pests controlled

Grain weevils; Common flour mite; Warehouse moth; Mill moth; Flour beetles; Rust-red grain beetle; Food mite; Stored grain pests,

Example applications

Stored gains - barley, wheat, oats, triticale; Non-cropped areas such as animal houses, domestic and industrial premises

Efficacy & activity

Efficiacy demonstrated via extensive use in the EU and field trials

Availability status

Current

Introduction & key dates

1973, first registration USA

GB regulatory status

GB COPR regulatory status

Approved

Date COPR inclusion expires

31/07/2029

GB LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

France

Date EC 1107/2009 inclusion expires

31/01/2027

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; Morocco

Chemical structure

Isomerism

None

Chemical formula

C₁₁H₂₀N₃O₃PS

Canonical SMILES

CCN(CC)C1=NC(=CC(=N1)OP(=S)(OC)OC)C

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

QHOQHJPRIBSPCY-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C11H20N3O3PS/c1-6-14(7-2)11-12-9(3)8-10(13-11)17-18(19,15-4)16-5/h8H,6-7H2,1-5H3

2D structure diagram/image available?

Yes

General status

Pesticide type

Insecticide; Acaricide

Substance groups

Organophosphate insecticide; Organophosphate acaricide; Organothiophosphate insecticide; Organothiophosphate acaricide; Pyrimidine insecticide; Pyrimidine acaricide

Minimum active substance purity

880 g kg⁻¹

Known relevant impurities

EU dossier - various metabolites

Substance origin

Synthetic

Mode of action

Broad-spectrum with contact and respiratory action. Acetylcholinesterase (AChE) inhibitor.

CAS RN

29232-93-7

EC number

249-528-5

CIPAC number

239

US EPA chemical code

108102

PubChem CID

34526

CLP index number

015-134-00-5

Molecular mass

305.33

PIN (Preferred Identification Name)

IUPAC name

O-2-diethylamino-6-methylpyrimidin-4-yl O,O-dimethyl phosphorothioate

CAS name

O-(2-(diethylamino)-6-methyl-4-pyrimidinyl) O,O-dimethyl phosphorothioate

Other status information

PAN listed Highly Hazardous Chemical; Subject to the provisions of the UK Poisons Act 1972

Relevant Environmental Water Quality Standards

UK non-statutory standard for the protection of aquatic life: freshwater and saltwater annual average; 0.015 µg l⁻¹; max acceptable conc: 0.05 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)

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Acarus chaetoxysilus, Acarus farris, Blattella germanica, Ephestia cautella, Meligethes aeneus, many others

Physical state

Clear to straw coloured liquid

Formulations

Property

Value

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

Certis
Syngenta

Example products using this active

Actellic 50EC
Actellic Smoke Generator no.20
Fumite Pirimiphos-Methyl Smoke

Formulation and application details

Available in a variety of formulations including emulsifiable conentrates and smoke generators

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

Moderate

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

250000

Xylene

250000

Methanol

250000

Acetone

250000

Ethyl acetate

Melting point (°C)

20.8

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

162

Flashpoint (°C)

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

1.58 X 10⁰⁴

Calculated

Log P

4.2

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data - observed in metabolism and farm animal feeding studies

Density (g ml⁻¹)

1.17

Dissociation constant pKa) at 25 °C

4.3

Weak acid

Vapour pressure at 20 °C (mPa)

2.0

Low volatility. 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)

0.06

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

Maximum UV-vis absorption L mol⁻¹ cm⁻¹

301nm = 3690, 270nm = 142000, 247nm = 22400, 220nm = 3390

Surface tension (mN m⁻¹)

58.5

at 21°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Moderately persistent

DT₅₀ (lab at 20 °C)

Non-persistent

DT₅₀ (field)

Moderately persistent

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

Lab studies DT₅₀ range 3-21 days, field studies range 18-67 days

Dissipation rate RL₅₀ (days) on plant matrix

Value

2.9

Note

Published literature RL₅₀ range 0.7-4.8 days, 2 undercover crops, various matrices, n=4

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

2.2

Note

Published literature RL₅₀ range 1.7-3.1 days,2 field & undercover grown crops, various matrices, n=5; Maize grain in store RL₅₀=90.5 days

Aqueous photolysis DT₅₀ (days) at pH 7

Value

0.2

Fast

Note

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

Value

117

Persistent

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

[Wheat grain: 70 wks @ 30 DegC, 50% RH; Modelled data], [Wheat grain: >28 wks @ 25 DegC, 65% RH; Lab study], [Milled, toasted maize flour (gofio): 167 days @ dark, ambient conditions; Field study], [Milled, toasted wheat flour (gofio): 25 days @ dark, ambient conditions; Field study], [Corn grain: 34.7 days @ 20-25 DegC, 40-60% RH; Lab study], [Rice: 26.4 days @ -20 DegC; Lab study]

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d (mL g⁻¹)

Slightly mobile

K_oc (mL g⁻¹)

1100

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

1.53

Calculated

Low leachability

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

Value

4.01 X 10^-02

Calculated

Note

Potential for particle bound transport index

Medium

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

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

Bio-concentration factor

BCF (l kg⁻¹)

741

Estimated

Threshold for concern

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

2-diethylamino-4-hydroxy-6-methylpyrimidine (Ref: R046382)

Stored grain; Animal; Rat; Human (Urine); Plant

O-2-ethylamino-6-methylpyrimidin-4-yl O,O-dimethylphosphorothioate (Ref: R036341)

Stored grain

2-ethylamino-6-methyl-pyrimidin-4-ol (Ref: R035510)

Animal; Human (Urine); Plant

O-2-ethylamino-6-methylpyrimidin-4-yl O-methyl phosphorothioate

desethyl-R402186

Animal

2-amino-4-hydroxy-6-methylpyrimidine (Ref: R004039)

Animal

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1414

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

0.5

Dog 12 wk

High

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

> 1695

Anas platyrhynchos

Moderate

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)

0.27

Apis mellifera

High

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

> 0.22

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)

Harmful

Chrysoperla carnea

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)

0.2

Oncorhynchus mykiss

Moderate

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

0.023

Oncorhynchus mykiss

Moderate

Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

3.45

Danio rerio EC₅₀ Embryo

Moderate

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

0.00021

Daphnia magna

High

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

0.00008

Daphnia magna

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)

0.039

Chironomus riparius 1 day

High

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)

1.0

Raphidocelis subcapitata

Moderate

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)

1414

Rat

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 4.7

Rat 4 hr (nose only)

Other Mammal toxicity endpoints

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

0.004

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

0.15

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

No data

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

0.02

Dermal penetration studies (%)

25-75

concentration dependent

Dangerous Substances Directive 76/464

List I; List II

Exposure Routes

Public

Bystanders are unlikely to become exposed due to patterns of use

Occupational

PPE/PPC recommended

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

Eye irritant

Phototoxicant

General human health issues

May cause contact dermatitis

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Hazard Class 9

CLP classification 2013

Health: H302
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

UN Number

UN3082

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

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

TRANSLATIONS

Language

Name

English

pirimiphos-methyl

French

pyrimiphos-methyle

German

Pirimiphos-methyl

Danish

pirimiphos-methyl

Italian

pirimifos-metile

Spanish

pirimifos-metil

Greek

pirimiphos-methyl

Polish

pirimifos metylu

Swedish

Hungarian

pirimifosz-metil

Dutch

pirimifos-methyl

Norwegian

Record last updated:	20/05/2025
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