Metaldehyde

Metaldehyde	Last updated: 21/08/2024
(Also known as: acetaldehyde tetramer)

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 Moderate alert: Drainflow: Moderately mobile	Ecotoxicity Moderate alert: Birds acute ecotoxicity: Moderate; Birds chronic ecotoxicity: Moderate; Fish acute ecotoxicity: Moderate; Daphnia acute ecotoxicity: Moderate; Bees acute oral ecotoxicity: Moderate; Earthworms chronic ecotoxicity: Moderate	Human health Moderate alert: Mammals acute toxicity: Moderate; Mammals chronic toxicity: Moderate; Reproduction/development effects

GENERAL INFORMATION

Description

A contact and systemic molluscicide bait for controlling slugs and snails

Example pests controlled

Slugs; Snails

Example applications

Ornamentals; Fruit trees and bushes; Various other fruits including avocado, citrus and berries; Vegetables including broccoli, cauliflower, cabbage and articokes

Efficacy & activity

Availability status

Current

Introduction & key dates

1936, first reported

UK regulatory status

UK COPR regulatory status

Approved

Date COPR inclusion expires

31/05/2026

UK LERAP status

None

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Poland/Austria

Date EC 1107/2009 inclusion expires

31/08/2026

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, USA, Morocco

Chemical structure

Isomerism

None

Chemical formula

C₈H₁₆O₄

Canonical SMILES

CC1OC(OC(OC(O1)C)C)C

Isomeric SMILES

None

International Chemical Identifier key (InChIKey)

GKKDCARASOJPNG-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C8H16O4/c1-5-9-6(2)11-8(4)12-7(3)10-5/h5-8H,1-4H3

2D structure diagram/image available?

Yes

Cambridge Crystallographic Data Centre diagrams

Common Name	Relationship	Link
metaldehyde	-

General status

Pesticide type

Molluscicide

Substance groups

Tetroxocane compound

Minimum active substance purity

985 g kg⁻¹

Known relevant impurities

EU dossier - Acetaldehyde max 1.5 g kg⁻¹

Substance origin

Synthetic

Mode of action

Contact and stomach action. Decreases the concentration of gamma-aminobutyric acid, an inhibitory neurotransmitter that causes CNS excitation.

CAS RN

108-62-3

EC number

203-600-2

CIPAC number

US EPA chemical code

053001

PubChem CID

61021

CLP index number

605-005-00-7

Molecular mass

176.21

PIN (Preferred Identification Name)

IUPAC name

2,4,6,8-tetramethyl-1,3,5,7-tetraoxacyclooctane

CAS name

2,4,6,8-tetramethyl-1,3,5,7-tetraoxacyclooctane

Other status information

Potential groundwater contaminant

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)

Not applicable

Fungicide Resistance Class (FRAC MOA class)

Not applicable

Examples of recorded resistance

Physical state

White or colourless crystalline solid

Formulations

Property

Value

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

Certis
Chiltern
De Sangosse
Mahhteshim
Ypsilon SA

Example products using this active

Certis Deal 5
Meridien
Carakol
Metalden
Metarex

Formulation and application details

Usually supplied in ready-to-use bait

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

188

Moderate

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

1500

Chloroform

530

Toluene

1730

Methanol

52.1

n-Hexane

Melting point (°C)

191

Sublimes

Boiling point (°C)

191

Sublimes

Degradation point (°C)

191

Sublimes

Flashpoint (°C)

(closed cup)

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

1.32 X 10⁰⁰

Calculated

Log P

0.12

Low

Fat solubility of residues

Solubility

Insoluble

Data type

Regulatory data based on LogP

Density (g ml⁻¹)

1.27

Dissociation constant pKa) at 25 °C

Not applicable

No dissociation

Vapour pressure at 20 °C (mPa)

6600

Highly volatile. 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)

3.50

Moderately volatile

Volatilisation as max % of applied dose lost

From plant surface

From soil surface

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

No significant absorption at any wavelength or pH

Surface tension (mN m⁻¹)

71.9

at 20°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

5.1

Non-persistent

DT₅₀ (lab at 20 °C)

5.1

Non-persistent

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

16.9

Non-persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU dossier lab studies DT₅₀ range 2.6-6.7 days (normalised), DT₉₀ range 8.5-22 days; Other sources: DT₅₀ 10 days (DW4)

Dissipation rate RL₅₀ (days) on plant matrix

Value

Note

Dissipation rate RL₅₀ (days) on and in plant matrix

Value

3.7

Note

Published literature RL₅₀ range 1.1-5.8 days, 3 field crops, various matrices, n=4

Aqueous photolysis DT₅₀ (days) at pH 7

Value

Stable

Note

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

Value

Stable

Note

Stable pH 5 to pH 9 at 25 °C

Water-sediment DT₅₀ (days)

12.2

Fast

Water phase only DT₅₀ (days)

11.5

Moderately fast

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)

Moderately mobile

K_oc (mL g⁻¹)

240

Notes and range

Freundlich

K_f (mL g⁻¹)

0.69

Moderately mobile

K_foc (mL g⁻¹)

77.0

¹/_n

0.93

Notes and range

EU dossier K_f range 0.432-0.962, K_foc range 38-149 mL g⁻¹, ¹/_n range 0.91-1.02

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

1.50

Calculated

Low leachability

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

Value

4.24 X 10^-03

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Moderately mobile

Calculated

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

1.7

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)

Low potential

CT₅₀ (days)

Negligible content after 28 days

Known soil metabolites

Metabolite

Major/Minor fraction

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

Estimated maximum occurrence fraction

Notes

acetaldehyde

Minor fraction

0.05

paraldehyde

Minor fraction

0.004

Known groundwater metabolites

None

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

acetaldehyde

Surface water; Sediment

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

283

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

> 10

Rat

High

(ppm diet)

> 200

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

134

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

196

Anas platyrhynchos

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 3460 mg kg feed⁻¹

Anas platyrhynchos

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

Anas platyrhynchos NOED

Moderate

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

> 1000

Eisenia foetida; Other data >10,000 (R3)

Low

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

Eisenia foetida

Moderate

Soil micro-organisms

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

Dose: 6.35 mg kg⁻¹ 28 Day

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)

> 113

Apis mellifera

Low

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

> 87.5

Apis mellifera

Moderate

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

Chronic

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) as Mortality LR₅₀ g ha⁻¹

> 350

Aphidius rhopalosiphi

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

> 350

Typhlodromus pyri

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)

Oncorhynchus mykiss

Moderate

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

37.5

Oncorhynchus mykiss

Low

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

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

> 78.4

Daphnia magna

Moderate

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

Daphnia magna

Low

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 - Acute 7 day EC₅₀, biomass (mg l⁻¹)

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

75.9

Scenedesmus subspicatus

Low

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

Mesocosm study data

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)

283

Rat

Moderate

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

5000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

> 15.0

Rat 4 hr

Other Mammal toxicity endpoints

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

0.02

Rat SF=100

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

0.3

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)

0.1

Dog SF=100

Dermal penetration studies (%)

0.23

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risk for bystanders

Occupational

Acceptable risk to operators using tractor mounted equipment but risk much higher if equipment is hand held.

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

Moderately toxic
Kidney and liver toxicant
US EPA - weak evidence to suggest possible human carcinogen

Handling issues

Property

Value and interpretation

General

Highly flammable
Avoid generation of dust as dust explosion possible
Not explosive or oxidising
IMDG Transport Hazard Class 4.1

CLP classification 2013

Health: H302
Handling: H228

WHO Classification

II (Moderately hazardous)

UN Number

UN1332

Waste disposal & packaging

Packaging Group III (minor danger)

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

metaldehyde

French

metaldehyde

German

Metaldehyd

Danish

metaldehyde

Italian

metaldeide

Spanish

metaldehido

Greek

Polish

metaldehyd

Swedish

Hungarian

metaldehyde

Dutch

metaldehyde

Norwegian

Record last updated:	21/08/2024
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