Description
Metam sodium is a crystalline material with an unpleasant
odor of sulfur compounds. It reacts in water to generate
methyl isothiocyanate, which is the active material. It is
applied as a freshly diluted solution in water.
Chemical Properties
A yellow to nearly clear yellow-green solution. Also described as a colorless to white crystalline solid.
Unpleasant sulfur-amine odor, similar to that of carbon
disulfide
Chemical Properties
White, crystalline solid. Readily soluble
in water; moderately soluble in alcohol; stable in
concentrated aqueous solution but decomposes in
dilute aqueous solution; unstable in moist soil.
Uses
Metam-sodium is a generator of methyl isothiocyanate. It is a soil
sterilant applied prior to planting and controls soil fungi, nematodes,
weed seeds and soil dwelling insects.
Uses
Metam Sodium is useful as an environmental-friendly and sustainable electrocatalyst for oxygen reduction reactions.
Uses
Fungicide, nematocide, weed killer, insecticide,
soil fumigant.
Definition
ChEBI: Metam-sodium is an organic sodium salt and an organosulfur insecticide. It has a role as a proherbicide, a proinsecticide, a profungicide and a pronematicide. It contains a metam(1-).
General Description
A yellow to light yellow-green aqueous solution with an odor of amine and sulfur that varies in intensity. Boiling point 230°F. Metham sodium has a specific gravity of 1.162. Metham sodium will decompose upon dilution to carbon disulfide, monomethylamine, methylisothiocyanate, and hydrogen sulfide. The decomposition products are flammable and toxic. The acute symptoms of exposure to metam sodium are excessive salivation, sweating, fatigue, weakness, nausea, headache, dizziness, eye and respiratory tract irritation, and skin irritation in the form of rashes. The spillage of a rail car tanker of metal sodium into the Sacramento River caused a major fish kill (over a million trout) along several miles of that river.
Air & Water Reactions
Slow reaction upon dilution produces toxic gases hydrogen sulfide and methylisothiocyanate. This reaction is accelerated by the addition of acid.
Reactivity Profile
METAM SODIUM is a dithiocarbamate. Flammable gases are generated by the combination of thiocarbamates and dithiocarbamates with aldehydes, nitrides, and hydrides. Thiocarbamates and dithiocarbamates are incompatible with acids, peroxides, and acid halides.
Hazard
Irritant to tissue, toxic to plants and vege-
tation.
Health Hazard
TOXIC; inhalation, ingestion or skin contact with material may cause severe injury or death. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution.
Fire Hazard
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.
Flammability and Explosibility
Not classified
Agricultural Uses
Fungicide; Nematicide, Herbicide, Soil fumi-
gant, Algaecide: A general soil biocide that is used to control weeds,
weed seeds, roots, tubers, rhizomes, insects, nematodes
and soil inhabiting fungi on all food and non-food crops.
Also used as a pre-planting fumigant in seed beds, vine
crops, fruit trees, row crops, flowers and ornamentals.
Environmental friendly; it breaks down after two weeks
into carbon dioxide, water, and sodium and sulfur in small
amounts. A U.S. EPA restricted Use Pesticide (RUP).
Registered for use in some EU countries
.
Trade name
A7-VAPAM®; BASAMID-FLUID®;
BUSAN®; CHAP-FUME®; DISCOVERY®; HERBATIM
(dihydrate)®; KARBATION®; KARBATION (di-
hydrate)®; MAPOSOL®; MAPOSOL (dihydrate)®;
METACIDE®; METAM (dihydrate)®; METAM-FLUID
BASF®; METHAM DIHYDRATE (dihydrate)®;
MONAM (dihydrate)®; N-869®; N 869 (dihydrate)®;
NEMATIN®; SECTAGON®; SISTAN®; SMDC (di-
hydrate)®; SOLASAN 500®; SOLESAN 500®;
SOMETAM®; TRAPEX®; TRIMATON (dihydrate)®;
TRIMATRON®; UCETAM®; VAPAM®; VAPAM (di-
hydrate)®; VAPOROOTER (dihydrate)®; VDM®; VPM
(dihydrate)®; VPM® Fungicide; VPN®; WOODFUME
VAPAM®
Contact allergens
Metham-Na is a fungicide nematocide of the dithiocarbamate group. Sensitization occurs among agricultural workers.
Potential Exposure
A dithiocarbamate fungicide, nematicide, herbicide, soil fumigant, and algaecide A general soil
biocide that is used to control weeds, weed seeds, roots,
tubers, rhizomes, insects, nematodes and soil inhabiting
fungi on all food and nonfood crops. Also used as a preplanting fumigant in seed beds, vine crops, fruit trees, row
crops, flowers and ornamentals. Environmental friendly; it
breaks down after two weeks into carbon dioxide, water,
and sodium and sulfur in small amounts. A United States
Environmental Protection Agency Restricted Use Pesticide
(RUP).
Metabolic pathway
Metam-sodium is a water soluble propesticide that decomposes to generate
the highly volatile and fungitoxic methyl isothiocyanate. The pathways
of metabolism of methyl isothiocyanate are described under its own
entry.
Shipping
UN3267 Corrosive liquid, basic, organic, n.o.s.,
Hazard class: 8; Labels: 8-Corrosive material, Technical
Name Required. UN2771 Dithiocarbamate and
Thiocarbamate pesticides, solid, toxic, Hazard Class: 6.1;
Labels: 6.1-Poisonous materials
Degradation
Metam-sodium can be stable in concentrated aqueous solution for several
weeks but is unstable when diluted. Decomposition is promoted by acids
and salts of heavy metals. DT
50 values for hydrolysis of metam-sodium
were 23.8, 180 and 45.6 hours at pH 5, 7 and 9 (25 °C), respectively. It is
sensitive to light and solutions exposed to sunlight had a DT
50 value of 1.6
hours (pH 7, 25 °C) (PM). In aqueous solution at high pH (9.5), metamsodium
was oxidatively degraded to form methyl isothiocyanate (2) and
elemental sulfur. At lower pH it was degraded non-oxidatively, affording
carbon disulfide, hydrogen sulfide, methy lamine, methyl isothiocyanate
(2) and N,N'-dimethylthiuram disulfide (3). It is noteworthy that methylamine
and carbon disulfide can react to yield methyl isothiocyanate (2)
that can in turn react with metam to produce N,N'-dimethylthiuram
disulfide (3). Methyl isothiocyanate (2) can react with methylamine
or hydrogen sulfide, giving dimethylthiourea (4) (Turner and Corden,
1963).
Incompatibilities
Slow reaction upon dilution in water
releasing toxic gases of hydrogen sulfide and methyl isothiocyanate. This reaction is accelerated by the addition of
acid. May liberate toxic gas when in contact with acids.
Combustible; vapors when heated or dust from dry material
may form explosive mixture in air. Dithiocarbamate esters
are combustible. They react violently with powerful oxidizers such as calcium hypochlorite. Poisonous gases are generated by the thermal decomposition of Dithiocarbamate
compounds, including carbon disulfide, oxides of sulfur,
oxides of nitrogen, hydrogen sulfide, ammonia, and methylamine. Thio and dithiocarbamates slowly decompose in
aqueous solution to form carbon disulfide and methylamine
or other amines. Such decompositions are accelerated by
acids. Flammable gases are generated by the combination
of dithiocarbamate with aldehydes, nitrides, and hydrides.
Dithiocarbamate are incompatible with acids, peroxides,
and acid halides. Corrosive to iron, copper brass and zinc
metals, especially in the presence of moisture. Heat alkalies
(lime), moisture can cause decomposition. Degradation produces ethylene thiourea.
Waste Disposal
Do not discharge into drains
or sewers. Dispose of waste material as hazardous waste
using a licensed disposal contractor to an approved landfill. Consult with environmental regulatory agencies for
guidance on acceptable disposal practices. Generators of
waste containing this contaminant (≥100 kg/mo) must
conform to EPA regulations governing storage, transportation, treatment, and waste disposal. A potential candidate for liquid injection incineration at a temperature
range of 650 to 1600C and a residence time 0.1 to
2 seconds. Also, a potential candidate for rotary kiln
incineration at a temperature range of 820 to 1600C and
residence times of seconds for liquids and gases,
and hours for solids.
