Methiocarb (Ref: OMS 93)

Methiocarb (Ref: OMS 93)	Last updated: 22/08/2024
(Also known as: mercaptodimethur; ENT 25726)

SUMMARY

Methiocarb is a carbamate pesticide. It has a low aqueous solubility, low volatility and, based on its chemical properties, it would not normally be expected to leach to groundwater. However, it has been detected in several countries. It is not normally persistent in soil or water systems. It is highly toxic to mammals, a cholinesterase inhibitor and a neurotoxin. It is also highly toxic to most fauna and flora including honeybees. The main exception is earthworms where the toxicity appears to be low.

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; GUS: Transition state; Drainflow: Slightly mobile	Ecotoxicity High alert: Birds acute ecotoxicity: High; Birds chronic ecotoxicity: High; Daphnia acute ecotoxicity: High; Daphnia chronic ecotoxicity: High; Bees acute contact ecotoxicity: High; Bees acute oral ecotoxicity: High	Human health High alert: Mammals acute toxicity: High; Mammals chronic toxicity: High; Endocrine disrupter; Acetyl cholinesterase inhibitor; Neurotoxicant

GENERAL INFORMATION

Description

A molluscicide and insecticide for control of a variety of plant pests. It also has application as a pheasant repellent.

Example pests controlled

Slugs and snails; Birds; Fruit flies; Mites; Leafhoppers; Aphids; Psylla, Meallybugs; Scale insects; Thrips; Some soil pests

Example applications

Most agricultural crops including maize, oilseed rape, pulses, root & tuber crops, lettuce; Fruit including cherries, blueberries, peaches

Efficacy & activity

Efficiacy is supported by long-term use across Europe and experimental work in various EU countries.

Availability status

Current

Introduction & key dates

1962, first introduced; 1972, first registered USA

GB regulatory status

GB COPR regulatory status

Not approved

Date COPR inclusion expires

Expired

GB LERAP status

No UK approval for use as a pesticide

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Not approved

Dossier rapporteur/co-rapporteur

Germany

Date EC 1107/2009 inclusion expires

Expired

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

Chemical structure

Isomerism

None

Chemical formula

C₁₁H₁₅NO₂S

Canonical SMILES

CC1=CC(=CC(=C1SC)C)OC(=O)NC

Isomeric SMILES

International Chemical Identifier key (InChIKey)

YFBPRJGDJKVWAH-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C11H15NO2S/c1-7-5-9(14-11(13)12-3)6-8(2)10(7)15-4/h5-6H,1-4H3,(H,12,13)

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
methiocarb	-

General status

Pesticide type

Insecticide, Molluscicide, Semiochemical

Substance groups

Carbamate insecticide; Phenyl methylcarbamate insecticide

Minimum active substance purity

980 g kg⁻¹

Known relevant impurities

EU dossier - None declared

Substance origin

Synthetic

Mode of action

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

CAS RN

2032-65-7

EC number

217-991-2

CIPAC number

165

US EPA chemical code

100501

PubChem CID

16248

CLP index number

006-023-00-2

Molecular mass

225.31

PIN (Preferred Identification Name)

IUPAC name

4-methylthio-3,5-xylyl methylcarbamate

CAS name

3,5-dimethyl-4-(methylthio)phenyl methylcarbamate

Other status information

Potential groundwater contaminant - previously detected in US, Australia, Mexico and Spain; Not approved for use as pelleted molluscicide in the EU.

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of aquatic life in freshwater and saltwater annual average 0.01 µg l⁻¹, max acceptable conc 0.16 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

Frankliniella occidentalis

Physical state

Colourless crystals

Formulations

Property

Value

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

Bayer CropScience
Interfarm
Mobay
Sundew Solutions Pty Ltd

Example products using this active

Decoy
Draza
Exit Wetex
Huron
Karan
Rivet
Mesurol
Guardian Sunsol Snail & Slug Bait

Formulation and application details

Often supplied for use as a seed treatment but also available as pellets or granules and applied directly to soil surface

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

Low

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

20000

Xylene

144000

Acetone

87000

Ethyl acetate

31000

1-Octanol

Melting point (°C)

118.5

Boiling point (°C)

311

Degradation point (°C)

300

Flashpoint (°C)

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

1.51 X 10⁰³

Calculated

Log P

3.18

High

Fat solubility of residues

Solubility

Soluble

Data type

Regulatory data

Density (g ml⁻¹)

1.25

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

1.50 X 10^-02

Low volatility

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

1.20 X 10^-04

Non-volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

pH 7: 203nm=44762, 223nm=12021, 267nm=2582
pH 2: 203nm=52548, 223nm=13026, 267nm=3030
pH 10: 219nm=23298, 267nm=11461

Surface tension (mN m⁻¹)

72.0

at 20°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Not likely to be readily biodegradable

Soil degradation (days) (aerobic)

DT₅₀ (typical)

2.94

Non-persistent

DT₅₀ (lab at 20 °C)

2.94

Non-persistent

DT₅₀ (field)

Moderately persistent

DT₉₀ (lab at 20 °C)

12.08

Non-persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

1.4

normalised geometric mean

Note

EU 2017 dossier lab studies DT₅₀ range 0.5-11.3 days, DT₉₀ range 1.7-48.1 days, Soils=5; Other sources: 30 days (DW4)

Dissipation rate RL₅₀ (days) on plant matrix

Value

8.0

Note

Published literature RL₅₀ range 1.7-11.5 days, 2 field & undercover growncrops, various matrices, n=3

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

2.4

Note

Published literature RL₅₀ range 2.35-2.40 days, 2 undercover grown crops, various matrices, n=2

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Moderately fast

Note

DT₅₀ 6 - 16 days for range of environmental scenarios

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

Value

Non-persistent

Note

pH sensitive: DT₅₀ 321 days at pH 5, 0.21 days at pH 9, all at 25 °C

Water-sediment DT₅₀ (days)

4.0

Fast

Water phase only DT₅₀ (days)

1.6

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)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

5.88

Slightly mobile

K_foc (mL g⁻¹)

660

¹/_n

0.832

Notes and range

EU 2017 dossier K_f range 0.43-0.9 mL g⁻¹, K_foc range 408-1000 mL g⁻¹, ¹/_n range 0.81-0.87, Soils=4

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.82

Calculated

Transition state

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

Value

5.89 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Slightly mobile

Calculated

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

9.5

Calculated using the Atkinson method. Assumed 1.5E+06 OH/cm³, 12 hr

Below the level of concern for long-range air transport

Bio-concentration factor

BCF (l kg⁻¹)

Lepomis macrochirus

Low potential

CT₅₀ (days)

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

methiocarb sulfoxide

Major fraction

0.588

methiocarb sulfoxide phenol

Major fraction

0.360

methiocarb sulfone phenol

Major fraction

0.198

methiocarb methoxy sulfone

Major fraction

0.132

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

methiocarb phenol; methiocab metabolite M03

Plant

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

Rat

High

Mammals - Short term dietary NOEL

(mg kg⁻¹)

1.3

Rat

High

(ppm diet)

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

4.3

Rat Reproductive NOAEL

High

Birds - Acute LD₅₀ (mg kg⁻¹)

Coturnix japonica

High

Birds - Short term dietary (LC₅₀/LD₅₀)

1071 mg kg feed⁻¹

Anas platyrhynchos

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

4.51

Anas platyrhynchos NOAEL

High

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

1322

Eisenia foetida

Low

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

0.161

Eisenia foetida

Moderate

Soil micro-organisms

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

Dose: 1.47 mg kg⁻¹ soil 28 Day

Collembola

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

< 37.5

Folsomia candida

Non-target plants

Honeybees (Apis spp.)

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

0.23

Apis mellifera

High

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

0.08

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

0.0415

Apis mellifera

Notes

Bumblebees (Bombus spp.)

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

19.3

Bombus terrestris

Moderate

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)

0.547

Apis mellifera Larva 72 hr

High

Mode of exposure

Bee brood development

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) as Mortality LR₅₀ g ha⁻¹ 48 hr

0.47

Aphidius rhopalosiphi Adult

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

33.7

Typhlodromus pyri

Beneficial insects (Ground beetles) as % Mortality at dose 677 g ha⁻¹

Poecilus cupreus

Aquatic ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

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

0.65

Oncorhynchus mykiss

Moderate

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

0.05

Oncorhynchus mykiss

Moderate

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

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

0.008

Daphnia magna

High

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

0.0001

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)

0.103

Chironomus riparius 48 hr EC₅₀

Moderate

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)

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

2.2

Scenedesmus subspicatus

Moderate

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

3.2

Unknown species

Low

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)

Rat

High

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

5000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 0.433

Rat 4 hr

Other Mammal toxicity endpoints

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

0.00025

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

0.0005

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

0.016

Rat Sf=100

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

0.00025

Dermal penetration studies (%)

1-2

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risk to bystanders as pesticide used normally as a seed dressing

Occupational

Negligible risk to operators

MRLs

European

EU MRL pesticide database

Great Britain

GB MRL Register

Notes

New GB MRL in place from 24 April 2023

Drinking Water Standards

Drinking Water MAC (μg l⁻¹)

Mammalian dose elimination route and rate

Rapid elimination as metabolites via the urine (84-90%) usually within 24hrs

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

Endocrine issues - Inhibition of androgen activity and increase of estrogen one

Handling issues

Property

Value and interpretation

General

Not explosive or oxidising
IMDG Transport Hazard Class 6.1
Not expected to auto-ignite; Not highly flammable

CLP classification 2013

Health: H301
Environment: H400, H410

WHO Classification

Ib (Highly hazardous)

UN Number

UN2757

Waste disposal & packaging

Packaging Group II (moderate danger)

Shelf-life, storage, stability and reactivity

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

TRANSLATIONS

Language

Name

English

methiocarb

French

methiocarb

German

Methiocarb

Danish

mercaptodimethur

Italian

metiocarb

Spanish

metiocarb

Greek

mercaptodimethur

Polish

metiokarb

Swedish

metiokarb

Hungarian

mercaptodimethur

Dutch

metiocarb

Norwegian

Record last updated:	22/08/2024
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