Methylthiocyanat

(Non-Specific -- Pesticide, Liquid, n.o.s.) Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Wear positive pressure breathing apparatus and special protective clothing. Remove and isolate contaminated clothing at the site. If water pollution occurs, notify appropriate authorities.

Avoid inhalation and skin contact. (Non-Specific -- Pesticide, Liquid, n.o.s.) Do not touch spilled material; stop leak if you can do so without risk. Use water spray to reduce vapors. For small spills, absorb with sand or other noncombustible absorbent material and place into containers for later disposal. For large spills, dike far ahead of spill for later disposal. (EPA, 1998)

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

0.18 [mg/m3]

2.0 [mg/m3]

12 [mg/m3]

For emergency situations, wear a positive pressure, pressure-demand, full facepiece self-contained breathing apparatus (SCBA) or pressure- demand supplied air respirator with escape SCBA and a fully-encapsulating, chemical resistant suit. (EPA, 1998)

Antidotes to cyanide poisoning include hydroxocobalamin and sodium nitrite, which release the cyanide from the cytochrome system, and rhodanase, which is an enzyme occurring naturally in mammals that combines serum cyanide with thiosulfate, producing comparatively harmless thiocyanate. Oxygen therapy can also be administered. (L97)

Exposure to high levels of cyanide for a short time harms the brain and heart and can even cause coma, seizures, apnea, cardiac arrest and death. Chronic inhalation of cyanide causes breathing difficulties, chest pain, vomiting, blood changes, headaches, and enlargement of the thyroid gland. Skin contact with cyanide salts can irritate and produce sores. (L96, L97)

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 8.3(SRC), determined from a structure estimation method(2), indicates that methyl thiocyanate is expected to have very high mobility in soil(SRC). Volatilization of methyl thiocyanate from moist soil surfaces is expected (SRC) based upon an estimated Henry's Law constant of 4.4X10-5 atm-cu m/mole(SRC), using a fragment constant estimation method(3). The potential for volatilization of methyl thiocyanate from dry soil surfaces is expected to exist(SRC) based on a measured vapor pressure of 12 mm Hg(4). Based upon a group contribution method for predicting the probability and rate of aerobic biodegradation(5), methyl thiocyanate has been estimated to biodegrade fast with primary biodegradation occurring over a period of days to weeks(SRC).

AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 8.3(SRC), determined from a structure estimation method(2), indicates that methyl thiocyanate is not expected to adsorb to suspended solids and sediment in water(SRC). Methyl thiocyanate is expected to volatilize from water surfaces(3,SRC) based on an estimated Henry's Law constant of 4.4X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Estimated volatilization half-lives for a model river and model lake are 20 hours and 8.6 days, respectively(3,SRC). According to a classification scheme(5), an estimated BCF value of 2.1(3,SRC), from an estimated log Kow(6,SRC), suggests that bioconcentration in aquatic organisms is low(SRC). Based upon a group contribution method for predicting the probability and rate of aerobic biodegradation(7), methyl thiocyanate has been estimated to be highly biodegraded with ultimate biodegradation occurring over a period of weeks(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methyl thiocyanate, which has an measured vapor pressure of 12 mm Hg at 25 °C(2,SRC), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase methyl thiocyanate is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be about 15 days(3,SRC).

Organic nitriles decompose into cyanide ions both in vivo and in vitro. Consequently the primary mechanism of toxicity for organic nitriles is their production of toxic cyanide ions or hydrogen cyanide. Cyanide is an inhibitor of cytochrome c oxidase in the fourth complex of the electron transport chain (found in the membrane of the mitochondria of eukaryotic cells). It complexes with the ferric iron atom in this enzyme. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted and the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Cyanide is also known produce some of its toxic effects by binding to catalase, glutathione peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, succinic dehydrogenase, and Cu/Zn superoxide dismutase. Cyanide binds to the ferric ion of methemoglobin to form inactive cyanmethemoglobin. (L97)

Using a structure estimation method based on molecular connectivity indices(1), the Koc for methyl thiocyanate can be estimated to be about 8.3(SRC). According to a recommended classification scheme(2), this estimated Koc value suggests that methyl thiocyanate is expected to have very high mobility in soil(SRC).

SYMPTOMATOLOGY (LARGELY INFERRED FROM ANIMAL TESTS): 1. INGESTION OF CONCN SOLN MAY LEAD TO VOMITING BECAUSE OF MUCOSAL IRRITATION. ... 5. MASSIVE SKIN CONTAMINATION WITH ORGANIC THIOCYANATE SOLN MAY PRODUCE SYSTEMIC POISONING...&...LOCAL IRRITATION & DERMATITIS. /ALIPHATIC THIOCYANATES/

SYMPTOMATOLOGY (LARGELY INFERRED FROM ANIMAL TESTS): 6. IN NONFATAL CASES EVIDENCE OF INJURIES TO THE LIVER & KIDNEYS MAY APPEAR. /ALIPHATIC THIOCYANATES/

...METHYL.../THIOCYANATE IS/ RAPIDLY ACTING /POISON/...OF HIGH POTENCY...

THE SIGNS AND SYMPTOMS OF KEROSENE POISONING ARE OFTEN DOMINANT AFTER EXPOSURES TO DILUTE SOLN OF THIOCYANATE INSECTICIDES. /ALIPHATIC THIOCYANATES/

Releases of CERCLA hazardous substances are subject to the release reporting requirement of CERCLA section 103, codified at 40 CFR part 302, in addition to the requirements of 40 CFR part 355. Methyl thiocyanate is an extremely hazardous substance (EHS) subject to reporting requirements when stored in amounts in excess of its threshold planning quantity (TPQ) of 10,000 lbs.

Methyl thiocyanate

1

20000

Toxic chemical that can be released at a facility.