Metam-sodium (Ref: N 869)

Metam-sodium (Ref: N 869)	Last updated: 31/03/2021
(Also known as: metham; methylcarbamodithioic acid, sodium salt; carbam; carbathion; metam; metham-sodium)

GENERAL INFORMATION

Description

A multi-action crop protection agent used as a pre-planting soil sterilant

Example pests controlled

Weed and disease suppression including control of annual bluegrass, chickweed, ragweed, nutgrass, morning glory; Sclerotina, club root and Rhizoctonia; Damping off; Some nematodes

Example applications

Vegetables; Fruit; Ornamentals; Fiber crops; Cover crops

Efficacy & activity

Availability status

Current

Introduction & key dates

1951, first reported

UK regulatory status

UK COPR regulatory status

Not approved

Date COPR inclusion expires

Not applicable

UK LERAP status

Not applicable

EC Regulation 1107/2009 (repealing 91/414)

EC Regulation 1107/2009 status

Approved

Dossier rapporteur/co-rapporteur

Belgium

Date EC 1107/2009 inclusion expires

30/06/2022

EU Candidate for substitution (CfS)

Yes - low ADI / ARfD / AOEL

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

C₂H₄NNaS₂

Canonical SMILES

CNC(=S)[S-].[Na+]

Isomeric SMILES

No data

International Chemical Identifier key (InChIKey)

AFCCDDWKHLHPDF-UHFFFAOYSA-M

International Chemical Identifier (InChI)

InChI=1S/C2H5NS2.Na/c1-3-2(4)5;/h1H3,(H2,3,4,5);/q;+1/p-1

2D structure diagram/image available?

Yes

General status

Pesticide type

Herbicide, Fungicide, Nematicide, Insecticide

Substance group

Carbamate

Minimum active substance purity

965 g kg⁻¹

Known relevant impurities

EU dossier - methylisothiocyanate <12g kg⁻¹ dry wt, N,N’-dimethylthiourea 23.0 g kg⁻¹ dry wt

Substance origin

Synthetic

Mode of action

Soil fumigant, binds to oxygen carrying molecules and prevents tissues from using oxygen.

CAS RN

137-42-8

EC number

205-293-0

CIPAC number

20.011

US EPA chemical code

039003

PubChem CID

5366415

Molecular mass

129.19

PIN (Preferred Identification Name)

IUPAC name

sodium N-methyldithiocarbamate

CAS name

methylcarbamodithioic acid sodium salt

Other status information

Marine Pollutant

Relevant Environmental Water Quality Standards

Herbicide Resistance Classification (HRAC)

Not known

Herbicide Resistance Classification (WSSA)

Not known

Insecticide Resistance Classification (IRAC)

Not applicable

Fungicide Resistance Classification (FRAC)

Not known

Examples of recorded resistance

Physical state

White crystalline powder

Related substances & organisms

metam-potassium

Formulations

Property

Value

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

Discovery
Sistan
Maposol
Ucetam

Example products using this active

United Phosphorus
New Farm Australia
Sinochem
Vapam

Formulation and application details

Often supplied as a soluble concentrate or liquid fumigant

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

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

578290

High

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

212.6

n-Heptane

261.1

Xylene

203.2

Ethyl acetate

218.8

Acetone

Melting point (°C)

88.5

Boiling point (°C)

Decomposes before boiling

Degradation point (°C)

150

Flashpoint (°C)

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

1.23 X 10^-03

Calculated

Log P

-2.91

Low

Bulk density (g ml⁻¹)

Dissociation constant pKa) at 25 °C

2.99

pKa(2) = 11.06

Vapour pressure at 20 °C (mPa)

57.5

Highly volatile

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

8.34 X 10^-06

Non-volatile

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

Neutral solution: 205.0nm = 7502.8, 248.0nm = 7942.3, 280.0nm = 9924.0, 290nm >10
Acidic solution: can not measured due to rapid hydrolysis
Basic solution: 248.0nm = 8042.5, 280.0nm = 9796.8, 290nm >10

Surface tension (mN m⁻¹)

72.0

at 21°C

Degradation

Property

Value

Source; quality score; and other information

Interpretation

General biodegradability

Soil degradation (days) (aerobic)

DT₅₀ (typical)

Non-persistent

DT₅₀ (lab at 20 °C)

0.01

Non-persistent

DT₅₀ (field)

Non-persistent

DT₉₀ (lab at 20 °C)

0.02

Non-persistent

DT₉₀ (field)

DT₅₀ modelling endpoint

Note

EU Dossier lab studies DT₅₀ range 4-22 minutes, DT₉₀ range 13-72 minutes; Other sources: up to 7 days

Dissipation rate RL₅₀ on plant matrix

Value

Note

Dissipation rate RL₅₀ on and in plant matrix

Value

Note

Aqueous photolysis DT₅₀ (days) at pH 7

Value

0.05

Fast

Note

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

Value

2.2

Non-persistent

Note

pH sensitive: DT₅₀ 1.9 days at pH 5, 4.5 days at pH 9, all at 25 °C

Water-sediment DT₅₀ (days)

0.07

Fast

Water phase only DT₅₀ (days)

Soil adsorption and mobility

Property

Value

Source; quality score; and other information

Interpretation

Linear

K_d

Mobile

K_oc

17.8

Notes and range

EU dossier data

Freundlich

K_f

K_foc

¹/_n

Notes and range

pH sensitivity

Fate indices

Property

Value

Source; quality score; and other information

Interpretation

GUS leaching potential index

2.32

Calculated

Transition state

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

Value

1.57 X 10^-02

Calculated

Note

Potential for particle bound transport index

Low

Calculated

Potential for loss via drain flow

Mobile

Calculated

Key metabolites

Metabolite

Formation medium

Estimated maximum occurrence fraction

1107/2009 relevancy

methyl isothiocyanate (Ref: SN-32866)

Soil

0.829

Major fraction, Relevant

Other known metabolites

Metabolite name and reference

Aliases

Formation medium / Rate

Estimated maximum occurrence fraction

Metabolising enzymes

N,N’-dimethylthiourea
Note: Toxicologically relevant

DMTU

Groundwater; Water/sediment

dimethylurea

DMU

Water/sediment

DMTD

Water/sediment

IMPURITY:

N,N’-dimethylthiourea

DMTU

Present in product

ECOTOXICOLOGY

Property

Value

Source; quality score; and other information

Interpretation

Bio-concentration factor

BCF (l kg⁻¹)

0.03

Estimated

Low potential

CT₅₀ (days)

Not available

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

896

Rat

Moderate

Mammals - Short term dietary NOEL

(mg kg⁻¹)

(ppm diet)

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

> 12

Rat Reproductive NOAEL

Moderate

Birds - Acute LD₅₀ (mg kg⁻¹)

211

Colinus virginianus

Moderate

Birds - Short term dietary (LC₅₀/LD₅₀)

> 448 mg kg bw⁻¹ day⁻¹

Colinus virginianus

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

Fish - Acute 96 hour LC₅₀ (mg l⁻¹)

> 0.175

Lepomis macrochirus

Moderate

Fish - Chronic 21 day NOEC (mg l⁻¹)

0.464

Oncorhynchus mykis

Moderate

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

0.99

Daphnia magna

Moderate

Aquatic invertebrates - Chronic 21 day NOEC (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)

Non-target plants

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

1.08

Pseudokirchneriella subcapitata

Moderate

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

Honeybees (Apis spp.)

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

> 36.2

Apis mellifera

Moderate

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)

> 36.2

Moderate

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 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)

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

Other soil macro-organisms

Acute LC₅₀ (mg kg⁻¹)

Chronic NOEC (mg kg⁻¹)

Other arthropod (1)

LR₅₀ g ha⁻¹

% Effect

-14.6

Reproduction [Dose: 608 kg ha⁻¹]
Aleochara bilineata

Other arthropod (2)

LR₅₀ g ha⁻¹

% Effect

Soil micro-organisms

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)

896

Rat

Moderate

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

2000

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

2.54

Rat 4 hr (whole body)

Other Mammal toxicity endpoints

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

0.001

Dog SF=100

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

0.1

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)

0.001

Dog SF=100

Dermal penetration studies (%)

1-12

concentration dependent

Dangerous Substances Directive 76/464

Exposure Routes

Public

Negligible risk to bystanders
Low risk of exposure via diet

Occupational

Low risk to operators and other workers utilising PPE/PPC

MRLs

European

EU MRL pesticide database

Notes

UK MRL levels for some commodities subject to change in late 2021

Drinking Water Standards

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

No data found

Eye irritant

Phototoxicant

No data found

General human health issues

Possible liver and urinary tract toxicant
USEPA - probable human carcinogen

Handling issues

Property

Value and interpretation

General

Corrosive
May liberate toxic gas when in contact with acids
Not explosive or oxidising
IMDG Transport Code is usually 8

CLP classification 2013

Health: H302, H314, H317
Environment: H400, H410

EC Risk Classification

Reproduction risk category 3: R63
Xn - Harmful: R22, R43
H - Handling risks: R31, R34
N - Dangerous for the environment: R50, R53

EC Safety Classification

S1/2, S26, S36/37/39, S45, S60, S61

WHO Classification

II (Moderately hazardous)

UN Number

2771 for active, variable with product, usually 3082 or 3267

Waste disposal & packaging

Spilled product is a hazardous waste and disposal must be at an approved manner
Packaging Group III (minor danger)

TRANSLATIONS

Language

Name

English

metam-sodium

French

metam

German

Metam

Danish

metam

Italian

metam

Spanish

metam

Greek

Polish

metam

Swedish

Hungarian

Dutch

metam-natrium

Record last updated:	31/03/2021
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