Chlorpyrifos (Ref: OMS 971)

Chlorpyrifos (Ref: OMS 971)	Last updated: 12/01/2021
(Also known as: ENT 27311; chlorpyriphos; Dowco 179; chlorpyrifos ethyl)

SUMMARY

An organophosphate insecticide no longer approved for use in the EU. It has a low aqueous solubility, is quite volatile and is non-mobile. There is a low risk of leaching to groundwater based on its chemical properties. It can be moderately persistent in soil systems but is not usually persistent in water systems. It is highly toxic to mammals, is classified as a reproduction toxicant, an acetyl cholinesterase inhibitor and a neurotoxicant. It is also a skin and eye irritant. It is highly toxic to birds, fish, aquatic inverterbrates and honey bees and moderately toxic to aquatic plants, algae and earthworms

GENERAL INFORMATION

Description

A broad spectrum organophosphorus insecticide and acaricide used to control soil and foliage pests

Example pests controlled

Scale; Wooly aphid; Leaf roller; Caterpillars; Corn earworm; Armyworm; Cutworms; Rootworms; Cockroaches; Flea beetles; Flies; Termites; Fire ants

Example applications

Cereals including barley, wheat; Cotton; Fruit including apples, pears, grapes, pineapples, bananas, strawberries, mango; Tomatoes; Nuts; Vegetables inclding carrots, cabbages, cauliflower, Brussel sprouts

Efficacy & activity

Chlorpyrifos has been used very successfully over a long period of time to control a wide range of foliar pests on agricultural crops.

Availability status

Current

Introduction & key dates

1965, first reported and introduced

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

Not applicable

UK LERAP status

Not applcable

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Spain/Poland

Date EC 1107/2009 inclusion expires

Not applicable

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

Also used in

Chemical structure

Isomerism

Chemical formula

C₉H₁₁Cl₃NO₃PS

Canonical SMILES

CCOP(=S)(OCC)OC1=NC(=C(C=C1Cl)Cl)Cl

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

SBPBAQFWLVIOKP-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C9H11Cl3NO3PS/c1-3-14-17(18,15-4-2)16-9-7(11)5-6(10)8(12)13-9/h5H,3-4H2,1-2H3

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
chlorpyrifos	-

General status

Pesticide type

Insecticide

Substance group

Organophosphate

Minimum active substance purity

970 g kg⁻¹

Known relevant impurities

EU dossier - Sulfotep <3.0 g kg⁻¹, Acetone insolubles <5.0 g kg⁻¹

Substance origin

Synthetic

Mode of action

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

CAS RN

2921-88-2

EC number

220-864-4

CIPAC number

221

US EPA chemical code

059101

PubChem CID

2730

Molecular mass

350.58

PIN (Preferred Identification Name)

O,O-diethyl O-(3,5,6-trichloropyridin-2-yl) phosphorothioate

IUPAC name

O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate

CAS name

O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate

Other status information

OSPAR soc; WFD priority substance; Marine Pollutant

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of aquatic life: Freshwater annual average 0.002 µg l⁻¹, max acceptable conc 0.01 µg l⁻¹; Saltwater annual average 0.001 µg l⁻¹, max acceptable conc 0.01 µg l⁻¹

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

Aedes aegypti, Aedes nigromaculis, Anopheles pharoensis, Bemisia argentifolii, Culex pipiens pipiens, Helicoverpa armigera, Plutella xylostella, Spodoptera litura, Tribolium castaneum, plus others

Physical state

White to light brown coloured crystals

Formulations

Property

Value

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

Alpha Chlorpyrifos
Ballad
Cyren
Dursban WG
Equity
Govern
Parapet
Hatchet
Lorsban

Example products using this active

Dow AgroSciences
Headland
Makhteshim-Agan
SumiAgro
Scotts

Formulation and application details

Usually supplied as an emulsifiable concentrates that is mixed with water and applied as a spray. Also supplied as granules for direct application to soil.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

1.05

Low

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

774000

Hexane

290000

Methanol

4000000

Ethyl acetate

4000000

Toluene

Melting point (°C)

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

170

Flashpoint (°C)

Not expected to self ignite; Not highly flammable

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

5.01 X 10⁰⁴

Calculated

Log P

4.7

High

Bulk density (g ml⁻¹)

1.51

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

1.43

Low volatility

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

0.478

Moderately volatile

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

Neutral soln: 203nm=21174, 230nm=10359, 290nm=5620
Acid soln: 203nm=22223, 230nm=10347, 290nm=5907
Alkaline soln: 242nm=9413, 290nm=1633, 323nm=6701

Surface tension (mN m⁻¹)

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Not readily biodegradable

Soil degradation (days) (aerobic)

DT₅₀ (typical)

386

Very persistent

DT₅₀ (lab at 20 °C)

386

Very persistent

DT₅₀ (field)

27.6

Non-persistent

DT₉₀ (lab at 20 °C)

250

EU 2005 data

Persistent

DT₉₀ (field)

113

DT₅₀ modelling endpoint

23.4

geometric mean

Note

EU 2017 dossier Lab studies DT₅₀ range 19.8->1000 days, Soils=8, Field - studies DT₅₀ range 0.32-88.9 days, DT₉₀ range 12.2-295 days, Soils =6

Dissipation rate RL₅₀ on plant matrix

Value

3.3

Note

Published literature RL₅₀ range 0.7-10.0 days, 11 field & undercover grown crops, various matrices, n=12

Dissipation rate RL₅₀ on and in plant matrix

Value

7.2

Note

Published literature RL₅₀ range 0.95-127.0 days, 30 field & undercover grown crops, various matrices, n=77

Aqueous photolysis DT₅₀ (days) at pH 7

Value

29.6

Slow

Note

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

Value

53.5

Moderately persistent

Note

pH sensitive 63-73 days at pH 5, 16-23 days at pH 8

Water-sediment DT₅₀ (days)

36.5

Moderately fast

Water phase only DT₅₀ (days)

Moderately fast

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

126.6

Non-mobile

K_oc

5509

Notes and range

EU 2017 dossier K_d range 55.2-295 mL g⁻¹, K_oc range 3187-7733 mL g⁻¹, Soils=5; Other sources: 6070 mL g⁻¹ (DW3), >5000 (E4)

Freundlich

K_f

91.6

Slightly mobile

K_foc

3954

¹/_n

0.92

Notes and range

EU 2017 dossier K_f range 45.2-234 mL g⁻¹, K_foc range 1520-5442 mL./g, ¹/_n range 0.86-0.97, Soils=5

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

0.58

Calculated

Low leachability

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

Value

1.10 X 10^-02

Calculated

Note

Potential for particle bound transport index

High

Calculated

Potential for loss via drain flow

Non-mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

3,5,6-trichloro-2-pyridinol

Soil

0.602

Major fraction, Relevant

2,3,5-trichloro-6-methoxypyridine

Soil

0.087

Minor fraction, Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

O-ethyl-O-(3,5,6-trichloro-2-pyridyl)phosphorothioic acid

phosphorothioate

Water (Hydrolysis)

>0.100

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

1374

(Other literature log BCF range 0.8-5.4 (R3)

Threshold for concern

CT₅₀ (days)

2.5

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

Rat

High

Mammals - Short term dietary NOEL

(mg kg⁻¹)

Rat 2 year

High

(ppm diet)

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

Rat Reproductive NOAEL

High

Birds - Acute LD₅₀ (mg kg⁻¹)

39.2

Colinus virginianus

High

Birds - Short term dietary (LC₅₀/LD₅₀)

203 ppm

Anas platyrhynchos

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

2.885

Anas platyrhynchos NOEC

High

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

0.025

Oncorhynchus mykiss

High

Fish - Chronic 21 day NOEC (mg l⁻¹)

0.00014

Oncorhynchus mykiss

High

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

0.00010

Daphnia magna

High

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

0.0046

Daphnia magna

High

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

0.00004

Americamysis bahia

High

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

0.000024

Chironomus riparius

High

Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)

0.0001

Chironomus riparius

High

Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)

Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)

0.53

Lemna minor

Moderate

Non-target plants

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

0.48

Unknown species

Moderate

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

0.043

Unknown species

Moderate

Honeybees (Apis spp.)

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

0.059

Apis mellifera

High

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

0.25

Apis mellifera

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)

> 1.58

Bombus terrestris 72hr

Moderate

Other literature values LD₅₀ range 0.09- 2.39 µg bee⁻¹

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

0.23

Bombus terrestris for methyl variant

High

Mason bees (Osmia spp.)

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

4.19

Osmia bicornis

Moderate

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)

Mode of exposure

Other pollinators (2)

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

Mode of exposure

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

129

Eisenia foetida

Moderate

Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)

12.7

Eisenia foetida

Moderate

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

0.2

Folsomia candida 35d LC₅₀

Chronic NOEC (mg kg⁻¹)

Other arthropod (1)

LR₅₀ g ha⁻¹

0.2

Aphidius colemani

% Effect

100

Mortality [Dose: Field rate]
Galendromus occidentalis

Other arthropod (2)

LR₅₀ g ha⁻¹

1986

Typhlodromus pyri

% Effect

100

Mortality [Dose: Field rate]
Neoseiulus fallacis

Soil micro-organisms

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

Dose: 4.8 kg ha⁻¹

Mesocosm study data

NOEAEC mg l⁻¹

0.1

EAC

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)

1250

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

0.1

Rat (whole body)

Other Mammal toxicity endpoints

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

0.001

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

0.005

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

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

0.001

Dermal penetration studies (%)

0.2-25

concentration & product dependent

Dangerous Substances Directive 76/464

List I; List II

Exposure Routes

Public

Possible risks of exposure when close to spraying activity

Occupational

PPE/PPC required to mitigate any expsoure risks

European MRLs

EU MRL pesticide database

Drinking Water Standards

Non-statutory WHO drinking water guideline 0.03 mg l⁻¹

UK EA QS database 2018

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

Eye irritant

Phototoxicant

General human health issues

Highly toxic by ingestion
Some studies indicate a link between chlorpyrifos metabolites and learning difficulties in children
Suspected cardiovascular & blood toxicant

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Code is 6.1

CLP classification 2013

Health: H301
Environment: H400, H410

EC Risk Classification

T - Toxic: R25
Xn - Harmful: R21, R43
N - Dangerous for the environment: R50, R53

EC Safety Classification

S1/2, S45, S60, S61

WHO Classification

II (Moderately hazardous)

UN Number

Active 2783, liquid products usually 3018

Waste disposal & packaging

Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

chlorpyrifos

French

chlorpyriphos

German

Chlorpyrifos

Danish

chlorpyrifos

Italian

clorpirifos

Spanish

clorpirifos

Greek

chlorpyrifos

Polish

chloropyrifos

Swedish

klorpyrifos

Hungarian

chlorpyrifos

Dutch

chloorpyrifos

Record last updated:	12/01/2021
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