Phosmet (Ref: OMS 232)

Phosmet (Ref: OMS 232)	Last updated: 31/10/2024
(Also known as: phthalophos; PMP; ENT 25705)

GENERAL INFORMATION

Description

An organophosphate substance that is now largely obsolete but was used, topically, as an insecticide

Availability status

Current

Introduction & key dates

circa 1962, introduced

Examples of veterinary uses

Used to treat mange and control lice, fleas and ticks

Examples of species treated

Dogs; Cats; Pigs; Cattle

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

None

Chemical formula

C₁₁H₁₂NO₄PS₂

Canonical SMILES

COP(=S)(OC)SCN1C(=O)C2=CC=CC=C2C1=O

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

LMNZTLDVJIUSHT-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C11H12NO4PS2/c1-15-17(18,16-2)19-7-12-10(13)8-5-3-4-6-9(8)11(12)14/h3-6H,7H2,1-2H3

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
phosmet	-

General status

Veterinary substance type

Insecticide, Acaricide

Substance groups

Organophosphate insecticide; Organophosphate acaricide; Organothiophosphate insecticide; Organothiophosphate acaricide; Phthalimide insecticide; Phthalimide acaricide

Minimum active substance purity

950 g kg⁻¹

Known relevant impurities

EU dossier - phosmet oxon 0.8 g kg⁻¹ max., iso phosmet: 0.4 g kg⁻¹

Substance origin

Synthetic

Mode of action

Non-systemic with predominately contact action. Acetylcholinesterase (AChE) inhibitor.

Molecular targets

[Cholinesterase, Inhibitor]

CAS RN

732-11-6

EC number

211-987-4

CIPAC number

318

US EPA chemical code

059201

PubChem CID

12901

CLP index number

015-101-00-5

Therapeutic Class

Antiparasitic products, insecticides & repellents: Ecoparasiticides, insecticides & repellents

ATCvet Code

QP53BB03

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

317.33

PIN (Preferred Identification Name)

IUPAC name

O,O-dimethyl S-phthalimidomethyl phosphorodithioate

CAS name

S-((1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)methyl) O,O-dimethyl phosphorodithioate

Other status information

Marine Pollutant; Evidence of use in third world countries

Relevant Environmental Water Quality Standards

Physical state

Off-white crystalline solid

Formulations

Property

Product

Manufacturer

Authorisation Route

Legal Class (GB/UK)

Example products (past and present) using this active

Formulation and application details

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

15.2

Moderate

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

53000

Xylene

62000

Ethyl acetate

29200

Methanol

1040

n-Heptane

Melting point (°C)

71.8

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

208.5

Flashpoint (°C)

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

6.31 X 10⁰²

Calculated

Log P

2.8

Moderate

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data based on LogP

Density (g ml⁻¹)

1.44

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

0.065

Low volatility

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

1.36 X 10^-03

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

24 hr

From soil surface

0.23

24 hr

Volatilisation is not considered critical for air pollution

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

Neutral solution: 221.9nm = 44668, 294.6nm = 1259
Acidic solution: 222.6nm = 42658, 295.6nm = 2399
Basic solution: 218.5nm = 16595

Surface tension (mN m⁻¹)

71.8

at 20°C

Refractive Index

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

3.2

Non-persistent

DT₅₀ (lab at 20 °C)

3.2

Non-persistent

DT₅₀ (field)

9.6

Non-persistent

DT₉₀ (lab at 20 °C)

15.65

Non-persistent

DT₉₀ (field)

Note

EU 2017 dossier Lab studies DT₅₀ 1.65-4.59 days, DT₉₀ range 5.48-25.82 days, Soils=4; field studies DT₅₀ range 1.5-10.6 days, USA, Soils=5

Manure DT₅₀ (days)

Aqueous photolysis DT₅₀ (days) at pH 7

Value

4.5

Moderately fast

Note

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

Value

0.3

Non-persistent

Note

pH sensitive: DT₅₀ 7.5 days at pH 5, 7.8 hours at pH 7, 4.5 minutes at pH 9, all at 25 °C

Water-sediment DT₅₀ (days)

Fast

Water phase only DT₅₀ (days)

Moderately fast

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)

6.78

Slightly mobile

K_oc (mL g⁻¹)

3534

Notes and range

EU 2017 dossier K_d range 1.21-13.51 mL g⁻¹, K_oc range 912-11258 mL g⁻¹, Soils=4

Freundlich

K_f (mL g⁻¹)

10.7

Slightly mobile

K_foc (mL g⁻¹)

3212

¹/_n

0.94

Notes and range

EU 2017 dossier K_f range 1.17-15.8 mL g⁻¹, K_foc range716-10400 mL g⁻¹, ¹/_n range 0.89-0.98, Soils=4

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

0.48

Calculated

Low leachability

Bio-concentration factor

BCF (l kg⁻¹)

Based on LogP < 3 Low risk (A5)

Low potential

CT₅₀ (days)

Not available

Known soil metabolites

Metabolite

Major/Minor fraction

$Click here for further information on Major/Minor fraction$

Estimated maximum occurrence fraction

Notes

phthalamic acid

Major fraction

0.169

phthalic acid

Minor fraction

0.083

desmethyl phosmet

Major fraction

0.108

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

O,O-dimethylphosphoric acid

Water

N-(methylsulfinylmethyl)-phthalamic acid

PaAMS(O)M

Rat (Urine)

N-(methylsulfonylmethyl)-phthalamic acid

PaAMS(O2)M

Rat (Urine)

phthalic anhydride

Plant

phthalimide

Plant

N-hydroxyphthalamic acid

Plant

Phosmet oxon

Plant

N-methlythiomethyl phthalimide

Animal (Liver)

N-methylsulfonylmethyl phthalamic acid

Animal (Liver)

N-hydroxymethylphthalimide

Water/sediment; Animal

O,O-dimethylphosphorodithioc acid

Water

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

113

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)

> 1068

Anas platyrhynchos

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

406 mg kg bw⁻¹ day⁻¹

Colinus virginianus

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

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

Eisenia foetida corr

Moderate

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

2.96

Eisenia foetida corr

Moderate

Soil micro-organisms

Nitrogen mineralisation: No significant adverse effect [Dose: 2.5 kg ha⁻¹]
Carbon mineralisation: No significant adverse effect [Dose: 3.4 kg ha⁻¹]

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

0.81

Folsomia candida corr

Non-target plants

Honeybees (Apis spp.)

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

0.22

Apis mellifera

High

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

0.37

Apis mellifera

High

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

Chronic as 10-day LDD₅₀ µg bee⁻¹ day⁻¹

0.092

Apis mellifera

Notes

[The residual time to 25% mortality (RT25) value for honeybees is 16.8 hrs (range 3-51 hrs)- USEPA data]

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)

6.1

Osmia cornifrons

Moderate

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) as Mortality LR₅₀ g ha⁻¹

2.64

Coccinella septempunctata Larva

Beneficial insects (Lacewings) as Mortality LR₅₀ g ha⁻¹

Chrysoperla carnea Larva

Beneficial insects (Parasitic wasps) as Mortality LR₅₀ g ha⁻¹ 48 hr

1.95

Aphidius rhopalosiphi Adult

Beneficial insects (Predatory mites) as Mortality LR₅₀ g ha⁻¹ 7 day

301

Typhlodromus pyri Adult

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)

0.24

Oncorhynchus mykiss

Moderate

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

0.032

Oncorhynchus mykiss

Moderate

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)

0.00078

Daphnia magna

High

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

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

0.016

Americamysis bahia

High

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)

0.07

Unknown species

Moderate

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

Mesocosm study data

NOEAEC mg l⁻¹

0.000813

Aquatic invertebrates

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)

113

Rat

Moderate

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

1000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 1.52

Rat 4 hr (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)

0.001

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

0.001

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

0.001

Dermal penetration studies (%)

0.1-4.0

concentration dependent

Dangerous Substances Directive 76/464

List I; List II

Exposure Routes

Public

Moderate risk to bystanders if present during spraying

Occupational

Risk of being absorbed via skin or the eyes - PPE/PPC essential

Mammalian dose elimination route and rate

Mainly eliminated in the urine (70-80%) but some lost via faeces (5-10%)

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

General human health issues

Highly toxic by all routes
US EPA - weak evidence to suggest possible human carcinogen

Handling issues

Property

Value and interpretation

General

Prevent generation of dust
Not explosive or oxidising
IMDG Transport Hazard Class 9
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H301, H302, H312, H332
Environment: H400, H410

WHO Classification

II (Moderately hazardous)

UN Number

UN3077

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

phosmet

French

phosmet

German

Phosmet

Danish

phosmet

Italian

fosmet

Spanish

fosmet

Greek

phosmet

Polish

fosmet

Swedish

Hungarian

phosmet

Dutch

fosmet

Norwegian

Record last updated:	31/10/2024
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