Metam sodium

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

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.

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

The Uses of Metam sodium

Metam Sodium is useful as an environmental-friendly and sustainable electrocatalyst for oxygen reduction reactions.

The Uses of Metam sodium

Fungicide, nematocide, weed killer, insecticide, soil fumigant.

The Uses of Metam sodium

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.

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. DT₅₀ 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 DT₅₀ 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.