Diazinon (Ref: OMS 469)

Diazinon (Ref: OMS 469)	Last updated: 11/01/2021
(Also known as: dimpylate; ENT 19507)

SUMMARY

Diazinon is a general purpose insecticide which no longer has approval for use in the EU. It is moderately soluble and highly volatile. Based on its cheiical properties it has a low risk of leaching to groundwater however, incidents of contamination have been noted and it should be considered a potential groundwater pollutant. It is non-persistent in soil but stable in aqueous environments. It is listed as a severe marine pollutant. Moderately toxic to mammals and earthworms. In humans and other mammals it is a neurotoxicant. Considered highly toxic to most aquatic organisms, honeybees and birds.

GENERAL INFORMATION

Description

A broad spectrum insecticide used to control sucking and chewing insects on a wide range of crops including top fruit. Also has livestock applications.

Example pests controlled

Bean fly; Thrips; Caterpillars; Cabbage white butterfly; Loopers; Cutworms; Livestock pests including mites, ticks, lice and biting flies

Example applications

Fruit including apples, pears, plums; Rice; Sugarcane; Horticultural crops; Vegetables including beans, brassicas, curcubits; onions

Efficacy & activity

Availability status

Current

Introduction & key dates

1953, first reported

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

Portugal

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

Also used in

Australia, USA

Chemical structure

Isomerism

None

Chemical formula

C₁₂H₂₁N₂O₃PS

Canonical SMILES

CCOP(=S)(OCC)OC1=NC(=NC(=C1)C)C(C)C

Isomeric SMILES

S=P(OCC)(OCC)Oc1nc(nc(c1)C)C(C)C

International Chemical Identifier key (InChIKey)

FHIVAFMUCKRCQO-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C12H21N2O3PS/c1-6-15-18(19,16-7-2)17-11-8-10(5)13-12(14-11)9(3)4/h8-9H,6-7H2,1-5H3

2D structure diagram/image available?

Yes

General status

Pesticide type

Insecticide, Acaricide, Repellent, Veterinary substance

Substance group

Organophosphate

Minimum active substance purity

950 g kg⁻¹ (without stabilizer)

Known relevant impurities

EU dossier - O,S-TEPP, S,S-TEPP, TEPP24 and diazoxon

Substance origin

Synthetic

Mode of action

Non-systemic with respiratory, contact and stomach action. Acetylcholinesterase (AChE) inhibitor.

CAS RN

333-41-5

EC number

206-373-8

CIPAC number

US EPA chemical code

057801

PubChem CID

3017

Molecular mass

304.35

PIN (Preferred Identification Name)

O,O-diethyl O-[6-methyl-2-(propan-2-yl)pyrimidin-4-yl] phosphorothioate

IUPAC name

O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate

CAS name

O,O-diethyl O-(6-methyl-2-(1-methylethyl)-4-pyrimidinyl) phosphorothioate

Other status information

Potential groundwater contaminant; Severe Marine Pollutant; Chemical subject to PIC regulations

Relevant Environmental Water Quality Standards

UK statutory standard for surface water quality: ‘Good’ for freshwater, transitional and coastal waters 0.01 µg l⁻¹, 0.02 µg l⁻¹ 95th percentile

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, Aphis pomi, Delia brassicae, Dialeurodes citri, Psilia rosae, many others

Physical state

Colourless to dark brown liquid

Formulations

Property

Value

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

Diazol 60EC
Knox-Out
DZN
Basin
Exodin
Nucidol
Diagran

Example products using this active

Makhteshim FCC
Ciba-Giegy
Nippon Kayaku

Formulation and application details

Available in a wide variety of formulations including concentrates for dilution and use as a crop spray, powders and impregnated collars for domestic pet use, shampoos, pour-ons and dips

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

Ethyl acetate

9000000

Acetone

9000000

Methanol

9000000

Toluene

Melting point (°C)

Not applicable

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

140

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

4.90 X 10⁰³

Calculated

Log P

3.69

High

Bulk density (g ml⁻¹)

1.11

Dissociation constant pKa) at 25 °C

2.6

Strong acid

Vapour pressure at 20 °C (mPa)

11.97

Highly volatile

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

6.09 X 10^-02

Non-volatile

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

Maxima at 246nm = 4050, 290nm = 20.86

Surface tension (mN m⁻¹)

49.5

at 20°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

9.1

Non-persistent

DT₅₀ (lab at 20 °C)

9.1

Non-persistent

DT₅₀ (field)

18.4

Non-persistent

DT₉₀ (lab at 20 °C)

209

Persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier range lab studies DT₅₀ range 8-23 days, DT₉₀ range 46-372 days; field studies Germany DT₅₀ 7.5-29.3 days, DT₉₀ range 24.9-97 days; Other sources: DT₅₀ 40 days (DW4)

Dissipation rate RL₅₀ on plant matrix

Value

2.4

Note

Published literature RL₅₀ range 0.8-5.2 days, 5 field & undercover grown crops, various matrices, n=6

Dissipation rate RL₅₀ on and in plant matrix

Value

3.5

Note

Published literature RL₅₀ range 1.0-9.6 days, 13 field & undercover grown crops, various matrices, n=13

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

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

Value

138

Persistent

Note

pH variable: DT₅₀ 12 days at pH 5, 77 days at pH 9

Water-sediment DT₅₀ (days)

10.4

Fast

Water phase only DT₅₀ (days)

4.3

Moderately fast

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

27.1

Slightly mobile

K_oc

609

Notes and range

EU dossier K_d range 3.7-113.5 mL g⁻¹, K_oc range 430-841 mL g⁻¹, Soils=2; Other literature studies: K_d range 0.84-19.72 mL g⁻¹; K_oc range 254-3779 mL g⁻¹, Soils=25

Freundlich

K_f

4.1

Slightly mobile

K_foc

643

¹/_n

0.860

Notes and range

EU dossier K_f range1.4-7.6 mL g⁻¹, K_foc range 413-760 mL g⁻¹, ¹/_n range 0.820-0.901, Soils=4; Other literature studies: K_f range 0.70-25.73 mL g⁻¹, K_foc range 259-4175 mL g⁻¹, ¹/_n range 0.79-1.25, Soils = 25

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.51

Calculated

Low leachability

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

Value

3.36 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

pyrimidinol (Ref: GS-27550)

Soil

0.820

Major fraction, Relevant

4-hydroxy-2-isopropyl-6-methylpyrimidine (Ref: CGA 14128)

Animal

Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

tetraethyl pyrophosphate (Ref: ENT 18771 )

TEPP

Not applicable

O,O,O,O-tetraethyl-thiopyrophosphate

O,S-TEPP

Not applicable

O,O,O,O-tetraethyl-dithiopyrophosphate

S,S-TEPP

Not applicable

2-(1-hydroxy-1-methyl)-ethyl-4-methyl-6-hydroxpyrimidine (Ref: GS 31144)

Rat (Urinary); Animal; Soil

O,O-diethyl O-(2-isopropyl-4-methylpyrimid-6-yl)phosphate
Note: CAS = 962-58-3; Toxic

diazoxon

Animal

diazinon hydroxylate

Animal

2-(1-hydroxymethyl)-ethyl-4-methyl-6-hydroxypyrimidine (Ref: CL-XIX-29)

Animal

2-isopropyl-4-hydroxymethyl-6-hydroxypyrimidine (Ref: JAK-III-57)

Animal

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

500

(Other literature log BCF range 0.7-3.5 (R3))

Threshold for concern

CT₅₀ (days)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

1139

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat

High

(ppm diet)

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

Birds - Acute LD₅₀ (mg kg⁻¹)

1.44

Anas platyrhynchos

High

Birds - Short term dietary (LC₅₀/LD₅₀)

8 mg kg bw⁻¹ day⁻¹

Anas platyrhynchos

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

3.1

Oncorhynchus mykiss

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

0.7

Oncorhynchus mykiss

Moderate

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

0.001

Daphnia magna

High

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

0.00056

Daphnia magna

High

Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)

0.0042

Americamysis bahia

High

Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)

0.023

Chironomus riparius

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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)

Non-target plants

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

6.4

Unknown species

Moderate

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

> 10

Unknown species

Low

Honeybees (Apis spp.)

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

0.13

High

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

0.09

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)

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)

0.007

Megachile rotundata

High

Mode of exposure

Contact

Other pollinators (2)

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

0.12

Nannotrigona perilampoides

High

Mode of exposure

Contact

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

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

811

48 hour
Aphidius rhopalosiphi

% Effect

Other arthropod (2)

LR₅₀ g ha⁻¹

0.153

Typhlodromus pyri

% Effect

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect
Carbon mineralisation: No significant adverse effect

Dose: 80 mg kg⁻¹ soil 28 days

Mesocosm study data

NOEAEC mg l⁻¹

0.0024

Fish

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)

1139

Rat

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 5.0

Rat

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 65.0 mg kg⁻¹

Rat

Intratracheal LD₅₀ = 210 mg kg⁻¹

Rat

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

0.0002

Dog SF=100

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

0.025

Rat SF=100

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

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

0.0002

Dog SF=100

Dermal penetration studies (%)

1.7-40.0

concentration dependent

Dangerous Substances Directive 76/464

List I; List II

Exposure Routes

Public

Possible risk to bystanders by inhalation

Occupational

Risk of exposure by dermal and inhalation routes
Personal protection clothing and equipment must be worn

European MRLs

EU MRL pesticide database

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

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

IARC Group 2A carcinogen; USEPA - not likely to be a human carcinogen
Endocrine issues - Estrogenic effect

Handling issues

Property

Value and interpretation

General

Not explosive
IMDG Transport Code is usually 6.1

CLP classification 2013

Health: H302
Environment: H400, H410

EC Risk Classification

Xn - Harmful: R22
N - Dangerous for the environment: R50, R53

EC Safety Classification

S2, S24/25, S60, S61

WHO Classification

II (Moderately hazardous)

UN Number

Usually 2783 or 2810

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

diazinon

French

diazinon

German

Diazinon

Danish

diazinon

Italian

diazinone

Spanish

diazinon

Greek

diazinon

Polish

diazynon

Swedish

diazinon

Hungarian

diazinon

Dutch

diazinon

Record last updated:	11/01/2021
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