Leptophos (Ref: OMS 1438 )

Leptophos (Ref: OMS 1438 )	Last updated: 22/05/2025
(Also known as: VCS 506; MBCP)

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 Low alert: Drainflow: Non-mobile Warning: Significant data are missing	Ecotoxicity High alert: Fish 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 obolete insecticide that is effective against lepidoptera and other insect pests

Example pests controlled

Tobacco cutworm (Prodenia litura); Grasshoppers; Fleas; Beetles; Aphids; Thrips

Example applications

Cereals; Cotton; Lawns; Rice; Sugarcane; Sugarbeet; Lettuce; Tomatoes; Tobacco

Efficacy & activity

Availability status

Considered obsolete but may be available in some countries

Introduction & key dates

1969, first reported

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Not applicable

GB LERAP status

No UK approval for use as a plant protection agent

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

Not applicable

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

Leptophos is a chiral molecule. The technical material is an isomeric mixture.

Chemical formula

C₁₃H₁₀BrCl₂O₂PS

Canonical SMILES

COP(=S)(C1=CC=CC=C1)OC2=CC(=C(C=C2Cl)Br)Cl

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

CVRALZAYCYJELZ-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C13H10BrCl2O2PS/c1-17-19(20,9-5-3-2-4-6-9)18-13-8-11(15)10(14)7-12(13)16/h2-8H,1H3

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
leptophos	-

General status

Pesticide type

Insecticide

Substance groups

Organophosphate insecticide; Phenyl phenylphosphonohioate insecticide

Minimum active substance purity

Approx 85% pure

Known relevant impurities

Substance origin

Synthetic

Mode of action

Non-systemic. Acetylcholinesterase (AchE) inhibitor.

CAS RN

21609-90-5

EC number

244-472-8

CIPAC number

None allocated

US EPA chemical code

525300

PubChem CID

30709

CLP index number

015-093-00-3

Molecular mass

412.07

PIN (Preferred Identification Name)

(E)-[O-(4-bromo-2,5-dichlorophenyl) O-methyl phenylphosphonothioate]

IUPAC name

(RS)-(O-4-bromo-2,5-dichlorophenyl O-methyl phenylphosphonothioate)

CAS name

O-(4-bromo-2,5-dichlorophenyl) O-methyl phenylphosphonothioate

Other status information

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, Plutella xylostella, Spodoptera littoralis, Pectinophora gossypiella

Physical state

White solid

Formulations

Property

Value

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

velsicol

Example products using this active

Phosvel
Velsicol 506

Formulation and application details

Common formulations include emulsifiable concentrates, wettable powders and granules

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

2.4

Low

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

1300000

benzene

470

Acetone

142000

Cyclohexane

Melting point (°C)

70.4

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

Flashpoint (°C)

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

2.04 X 10⁰⁶

Calculated

Log P

6.31

High

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.53

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

1.999

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)

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

Very persistent

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

6.7

Note

Published literature RL₅₀ range 3.0-17.0 days, 9 field grown crops, various matrices, n=9

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Note

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

Value

38.5

Moderately persistent

Note

pH sensitive: 245 days at pH 6, 38.5 days at pH 7, 16 days at pH 8

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)

Non-mobile

K_oc (mL g⁻¹)

33000

Notes and range

K_oc range 1175-117490 mL g⁻¹

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)

6058

High potential

CT₅₀ (days)

not available

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

43.0

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)

> 1500

Coturnix japonica

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)

> 3400

Lumbricus terrestris

Low

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)

> 0.011

Oncorhynchus mykiss

High

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)

0.002

Daphnia magna

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 (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)

43.0

Rat

High

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

800

Rabbit

Mammals - Inhalation LC₅₀ (mg l⁻¹)

2.7

Rat

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

List I

Exposure Routes

Public

Occupational

May occur through dermal contact and inhalation of dust and sprays

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

Highly toxic

Handling issues

Property

Value and interpretation

General

Avoid generation of dust
IMDG Transport Hazard Class 6.1

CLP classification 2013

Health: H301, H312, H370
Environment: H400, H410

WHO Classification

Ia (Extremely hazardous)

UN Number

UN2783

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

leptophos

French

German

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	22/05/2025
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