Methyl isothiocyanate

H301: Toxic if swallowed [Danger Acute toxicity, oral]

H314: Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]

H317: May cause an allergic skin reaction [Warning Sensitization, Skin]

H331: Toxic if inhaled [Danger Acute toxicity, inhalation]

H400: Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

H410: Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]

P260, P261, P264, P270, P271, P272, P273, P280, P301+P316, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P330, P333+P317, P362+P364, P363, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

H301 (100%): Toxic if swallowed [Danger Acute toxicity, oral]

H310+H330 (66.5%): Fatal in contact with skin or if inhaled [Danger Acute toxicity, dermal; acute toxicity, inhalation]

H310 (90.1%): Fatal in contact with skin [Danger Acute toxicity, dermal]

H314 (100%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]

H317 (100%): May cause an allergic skin reaction [Warning Sensitization, Skin]

H318 (66.5%): Causes serious eye damage [Danger Serious eye damage/eye irritation]

H330 (90.1%): Fatal if inhaled [Danger Acute toxicity, inhalation]

H335 (66.5%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H400 (100%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]

H410 (100%): Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]

P260, P261, P262, P264, P264+P265, P270, P271, P272, P273, P280, P284, P301+P316, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P354+P338, P316, P317, P319, P320, P321, P330, P333+P317, P361+P364, P362+P364, P363, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 161 reports by companies from 6 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H310: Fatal in contact with skin [Danger Acute toxicity, dermal]

H315: Causes skin irritation [Warning Skin corrosion/irritation]

H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H330: Fatal if inhaled [Danger Acute toxicity, inhalation]

H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

H372: Causes damage to organs through prolonged or repeated exposure [Danger Specific target organ toxicity, repeated exposure]

P260, P261, P262, P264, P264+P265, P270, P271, P273, P280, P284, P301+P316, P302+P352, P304+P340, P305+P351+P338, P308+P316, P316, P319, P320, P321, P330, P332+P317, P337+P317, P361+P364, P362+P364, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

H371: May cause damage to organs [Warning Specific target organ toxicity, single exposure]

H373: May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

P260, P261, P262, P264, P264+P265, P270, P271, P280, P284, P301+P316, P302+P352, P304+P340, P305+P351+P338, P308+P316, P316, P319, P320, P321, P330, P332+P317, P337+P317, P361+P364, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Warning: Methyl isothiocyanate is very toxic and highly irritating to skin, mucous membranes, and eyes. Caution is advised.

Signs and Symptoms of Acute Methyl Isothiocyanate Exposure: Signs and symptoms of acute exposure to methyl isothiocyanate is an irritant to eyes, skin, lungs, and the mucous membranes of the gastrointestinal tract. Respiratory symptoms include burning or irritation of the nose and throat, cough, laryngitis, chest pain, and asthmatic syndrome (chemical bronchitis with severe bronchospasm). Also, headache, vomiting, abdominal pain, insomnia, and anxiety neurosis with depression, or paranoid tendencies may be produced.

Emergency Life-Support Procedures: Acute exposure to methyl isothiocyanate exposure may require decontamination and life support for the victims. Emergency personnel should wear protective clothing appropriate to the type and degree of contamination. Air-purifying or supplied-air respiratory equipment should also be worn, as necessary. Rescue vehicles should carry supplies such as plastic sheeting and disposable plastic bags to assist in preventing spread of contamination.

Inhalation Exposure:

1. Move victims to fresh air. Emergency personnel should avoid self-exposure to methyl isothiocyanate.

2. Evaluate vital signs including pulse and respiratory rate and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.

3. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

4. Transport to a health care facility.

Dermal/Eye Exposure:

1. Remove victims from exposure. Emergency personnel should avoid self-exposure to methyl isothiocyanate.

3. Remove contaminated clothing as soon as possible.

4. If eye exposure has occurred, eyes must be flushed with lukewarm water for at least 15 minutes.

5. Wash exposed skin areas THOROUGHLY with soap and water.

6. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures.

7. Transport to a health care facility.

Ingestion Exposure:

1. Evaluate vital signs including pulse and respiratory rate and note any trauma. If no pulse is detected, provide CPR. If not breathing, provide artificial respiration. If breathing is labored, administer 100% humidified oxygen or other respiratory support.

2. DO NOT induce vomiting.

4. Give the victims water or milk: children up to 1 year old, 125 mL (4 oz or 1/2 cup); children 1 to 12 years old, 200 mL (6 oz or 3/4 cup); adults, 250 mL (8 oz or 1 cup). Water or milk should only be given if victims are conscious and alert.

5. Activated charcoal may be administered if victims are conscious and alert. Use 15 to 30 gm (1/2 to 1 oz) for children, 50 to 100 gm (1-3/4 to 3-1/2 oz) for adults, with 125 to 250 mL (1/2 to 1 cup) of water.

6. Promote excretion by administering a saline cathartic or sorbitol to conscious and alert victims. Children require 15 to 30 gm (1/2 to 1 oz) of cathartic; 50 to 100 gm (1-3/4 to 3-1/2 oz) is recommended for adults.

7. Transport to a health care facility. (EPA, 1998)

General First Aid:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

(Non-Specific -- Pesticide, Solid, n.o.s.) Move container from area if you can do so without risk. Wear self-contained (positive pressure if available) breathing apparatus and full protective clothing.

(Non-Specific -- Pesticide, Solid, n.o.s.) Small fires: dry chemical, carbon dioxide, water spray, or foam. Large fires: water spray, fog, or foam. (EPA, 1998)

Evacuation: If fire becomes uncontrollable or container is exposed to direct flame - consider evacuation of one-third (1/3) mile radius.

If material on fire or involved in fire: Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Solid streams of waiter may be ineffective. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. use "alcohol" foam, dry chemical or carbon dioxide.

Extinguishing Media: Water fog, foam, CO2, dry chemical. /MITC-Fume/

Evacuate enclosed and surrounding areas. If smoke and fumes cannot be avoided, use proximity suit and self-contained breathing apparatus. Use water spray to cool containers and disperse vapors. Keep spills away from sources of ignition. /MITC-Fume/

Where there is a fire involving isocyanates, carbon dioxide or powder extinguishers must be employed. Firemen must be equipped with self-contained breathing apparatus. /Isocyanates/

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· Ventilate closed spaces before entering, but only if properly trained and equipped.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· All equipment used when handling the product must be grounded.

· Do not touch or walk through spilled material.

· Stop leak if you can do it without risk.

· Prevent entry into waterways, sewers, basements or confined areas.

· A vapor-suppressing foam may be used to reduce vapors.

Small Spill

· Absorb with earth, sand or other non-combustible material and transfer to containers for later disposal.

· Use clean, non-sparking tools to collect absorbed material.

Large Spill

· Dike far ahead of liquid spill for later disposal.

· Water spray may reduce vapor, but may not prevent ignition in closed spaces.

Excerpt from ERG Guide 131 [Flammable Liquids - Toxic]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 2477 datasheet.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

Immediate precautionary measure

· Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

· For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.

· For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary.

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.

Small spill:

- ISOLATE in all directions: 30 m (100 ft)

Large spill:

- PROTECT people from downwind during DAY time: 0.1 km (0.1 mi)

- PROTECT people from downwind during NIGHT time: 0.1 km (0.1 mi)

- PROTECT people from downwind during DAY time: 0.3 km (0.2 mi)

- PROTECT people from downwind during NIGHT time: 0.4 km (0.3 mi)

Decontamination of spilled isocyanates and disposal of isocyanate waste are best conducted by using aqueous ammonia (3-8% concentrated ammonia solution in 90-95% water with 0.2-5% liquid detergent) or aqueous sodium carbonate (5-10% sodium carbonate in 90-95% water and 0.2-5% liquid detergent). An alcoholic solution (50% ethanol, isopropyl alcohol, or butanol; 45% water; and 5% concentrated ammonia) may be preferred because of the low miscibility of isocyanates with water. /Isocyanates/

Steps to be taken in case material is released or spilled: Cover with cold water. Product will solidify. Recycle, if possible or add solid scale in small amounts to drum with 10% aqueous ammonia solution. Product will react with ammonia to form N-Methyl thiourea. /MITC-Fume/

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

For terrestrial uses: Do not apply directly to water or to areas where surface water is present or to intertidal areas below the mean high water mark. /MLPC Methylisothiocyanate (MITC)/

Users must wash hands before eating, drinking, chewing gum, using tobacco, or using the toilet. Users must remove clothing immediately if pesticide gets inside. Then wash thoroughly and put on clean clothing. Users must remove PPE immediately after handling this product. Wash the outside of gloves before removing. As soon aSJlOssible, wash thoroughly. /MLPC Methylisothiocyanate (MITC)/

Excerpt from ERG Guide 131 [Flammable Liquids - Toxic]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. A vapor-suppressing foam may be used to reduce vapors.

SMALL SPILL: Absorb with earth, sand or other non-combustible material and transfer to containers for later disposal. Use clean, non-sparking tools to collect absorbed material.

LARGE SPILL: Dike far ahead of liquid spill for later disposal. Water spray may reduce vapor, but may not prevent ignition in closed spaces. (ERG, 2024)

Store only in closed original container to prevent leakage. Store only in cool, well-ventilated, locked areas, away form food and feedstuff, out of reach of children and irresponsible persons. Avoid exposure to heat and/or direct sunlight. Do not drop container onto or slide across sharp objects. /MLPC Methylisothiocyanate (MITC)/

Isocyanates are transported in railroad tank cars, tank trucks, tanks in ships, containers, and drums. They are stored in steel tanks and processed in steel equipment. For long-term storage stainless steel is recommended. To avoid contamination by atmospheric moisture, a dry air or inert gas blanket is essential. /Isocyanates/

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE.

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

TIH (Toxic Inhalation Hazard) - Term used to describe gases and volatile liquids that are toxic when inhaled. Some are TIH materials themselves, e.g., chlorine, and some release TIH gases when spilled in water, e.g., chlorosilanes. [ERG 2016].

AEGL 1: Notable discomfort, irritation, or certain asymptomatic non-sensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure (Unit: ppm)

AEGL 2: Irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape (Unit: ppm)

AEGL 3: Life-threatening health effects or death (Unit: ppm)

AEGLs Status: Final

0.27 [mg/m3]

17 [mg/m3]

50 [mg/m3]

CAUTION: The majority of these products have a very low flash point. Use of water spray when fighting fire may be inefficient.

CAUTION: Methanol (UN1230) will burn with an invisible flame. Use an alternate method of detection (thermal camera, broom handle, etc.)

Small Fire

· Dry chemical, CO2, water spray or alcohol-resistant foam.

Large Fire

· Water spray, fog or alcohol-resistant foam.

· If it can be done safely, move undamaged containers away from the area around the fire.

· Dike runoff from fire control for later disposal.

· Avoid aiming straight or solid streams directly onto the product.

Fire Involving Tanks, Rail Tank Cars or Highway Tanks

· Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.

· Cool containers with flooding quantities of water until well after fire is out.

· Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.

· ALWAYS stay away from tanks in direct contact with flames.

· For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn.

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)

Applicators and other handlers must wear: long-sleeved shirt and long pants; socks and chemical resistant footwear; goggles or face shield; chemicalresistant gloves (such as barrier laminate, butyl rubber, nitrile rubber, neoprene rubber, polyvinyl chloride, vitron). /MLPC Methylisothiocyanate (MITC)/

Under normal use, there is no need for respiratory protection. If MITC-FUME is to be used in an enclosed area, a positive pressure supplied air respirator equipped with full face piece should be used during any operation where there Is potential for release of this product to workplace air. /MITC-Fume/

When applying in enclosed areas, wear a mask or pesticide respirator jointly approved by the Mining Enforcement and Safety Administration and National Institute for Occupational Safety and Health. /MLPC Methylisothiocyanate (MITC)/

NIOSH investigators recommend that dermal exposures to isocyanate-containing substances be prevented. Employers should provide protective clothing, gloves, and footwear that is impervious to isocyanate--containing compounds. The protective clothing should either be disposed or laundered after each use (e.g., at the end of the work shift). The gloves should be elbow-length and made of an isocyanate-resistant material. /Isocyanate-containing substances/

Face-shields and aprons should be used whenever there is a possibility of a splash or a spill of liquids containing isocyanate-containing materials. /Isocyanate-containing substances/

Methyl isothiocyanate appears as a colorless liquid with a sharp odor. Lethal by inhalation of even small quantities of vapor. Does not have odor warning characteristics at low concentrations. Do not rely on the sense of smell to warn about the presence of vapors. Denser than water. May cause tearing and irritate the eyes, skin, nose and throat.

Colorless crystals that sublime at room temperature; mp = 36 deg C; [HSDB] Pale yellow low melting solid with an acrid odor; mp = 30-34 deg C; [Alfa Aesar MSDS]

Colourless to tan liquid; Pungent, penetrating mustard-like odour

Colorless crystals

Solid at room temperature but sublimes directly to a gas.

Horseradish-like odor

246 °F at 760 mmHg (EPA, 1998)

117.00 to 118.00 °C. @ 760.00 mm Hg

117-118 °C

119 °C @760 [mm Hg]

95 to 97 °F (EPA, 1998)

95 °F (35 °C) (closed cup). /MITC-Fume/

Readily soluble in common organic solvents, such as ethanol, methanol, acetone, cyclohexanone, dichloromethane, chloroform, carbon tetrachloride, benzene, xylene, petroleum ether, and mineral oils.

Very soluble in ethyl ether

In water, 7.6X10+3 mg/L at 25 °C

7.6 mg/mL at 20 °C

Very slightly soluble in water; freely soluble in ether

Soluble (in ethanol)

1.069 at 98.6 °F (EPA, 1998) - Denser than water; will sink

1.0691 at 37 °C/4 °C

0.938-0.942

1.069 @ 37°C

2.53 (Air = 1)

39.29 mmHg (USCG, 1999)

3.54 [mmHg]

3.54 mm Hg at 25 °C

19 [mm Hg] @20 °C

log Kow = 0.94

698 °F. /MITC-Fume/

When heated to decomposition it emits very toxic fumes of /nitrogen oxides & sulfur oxides/.

Carbon oxysulfide, hydrogen sulfide and methylamine may be formed upon contact with hydrolyzing agents (e.g. water). Violent reactions and formation of sulfur dioxide occur upon reaction with oxidants. /MITC-Fume/

Corrosive to iron, zinc and other metals

Odor Threshold Low: 1.7 [ppm]

In the olfactory threshold study, 33 individuals (16 males, 17 females) with a mean age of 25 years (range, 18 to 34 years) were tested. They were exposed to three positive control odorants, pyridine, acetic acid, and n-butyl alcohol, as well as to MITC. The technician chose the odorant and concentration level. The odorant was dispensed in double blind fashion from one of three presentation ports. The subject was responsible for identifying from which of the presentation ports the odorant was dispersed. A 30-second rest period between exposures was permitted in order to allow the subject to recover prior to the next exposure. The operator tested each subject over the range of concentrations for each odorant until he was assured that the threshold had been adequately ascertained. A standard procedure was employed in order to make this determination. The observed odor threshold for MITC ranged from 0.2 to 8 ppm with a geometric mean of 1.7 ppm. ...

Index of refraction: 1.5258 for 37 °C/D

1.495-1.499

pKa = 12.30

Saturated concentration: 75.6 g/cu m @ 20 °C; 115 g/cu m @ 30 °C

Unstable and reactive. Rapidly hydrolyzed by alkalis, more slowly in acidic and neutral solutions. ... Sensitive to oxygen and light.

MP: 25.3-27.6 °C; Density: 1.0537 at 40 °C /Technical grade/

Highly flammable. Methyl isothiocyanate reacts with water to form carbon dioxide and methylamine gases.

Isocyanates and Isothiocyanates

Highly Flammable

Water-Reactive

Isocyanates and thioisocyanates, such as METHYL ISOTHIOCYANATE, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Polyurethanes are formed by the condensation reaction of diisocyanates with, for example, ethyl glycol.

... Can react vigorously with oxidizing materials.

Rapidly hydrolyzed by alkalis, more slowly in acidic and neutral solutions.

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)

No indication of carcinogenicity to humans (not listed by IARC).

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)

Inhalation (L96) ; oral (L96) ; dermal (L96)

Cyanide poisoning is identified by rapid, deep breathing and shortness of breath, general weakness, giddiness, headaches, vertigo, confusion, convulsions/seizures and eventually loss of consciousness. (L96, L97)

Neurotoxin - Other CNS neurotoxin

Dermatotoxin - Skin burns.

Lacrimator (Lachrymator) - A substance that irritates the eyes and induces the flow of tears.

Skin Sensitizer - An agent that can induce an allergic reaction in the skin.

Toxic Pneumonitis - Inflammation of the lungs induced by inhalation of metal fumes or toxic gases and vapors.

LC50 (rat) = 540 mg/m3

LD50: 90-104 mg/kg (Oral, Mouse) (T58)

LD50: 54 mg/kg (Intraperitoneal, Rat) (T14)

LD50: 59 mg/kg (Subcutaneous, Rat) (T14)

LD50: 2780 mg/kg (Dermal, Rat) (T14)

LC50: 1900 mg/m3 over 1 hour (Inhalation, Rat) (T14)

LD50 Mouse skin 2780 mg/kg

LD50 Mouse oral 97 mg/kg

LD50 Mouse male percutaneous 1870 mg/kg

LD50 Rat ip 54 mg/kg

For more Non-Human Toxicity Values (Complete) data for METHYL ISOTHIOCYANATE (10 total), please visit the HSDB record page.

EYES: irrigate opened eyes for several minutes under running water.

INGESTION: do not induce vomiting. Rinse mouth with water (never give anything by mouth to an unconscious person). Seek immediate medical advice.

SKIN: should be treated immediately by rinsing the affected parts in cold running water for at least 15 minutes, followed by thorough washing with soap and water. If necessary, the person should shower and change contaminated clothing and shoes, and then must seek medical attention.

INHALATION: supply fresh air. If required provide artificial respiration.

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Isocyanates, aliphatic thiocyanates, and related compounds/

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Monitor for seizures and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 mL of water for dilution if the patent can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Isocyanates, aliphatic thiocyanates, and related compounds/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag valve mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Treat exposure to Lethane 60 Lethane 384, Thanite, methyl, ethyl, or isopropyl thiocyanates with the cyanide antidote kit. ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Isocyanates, aliphatic thiocyanates, and related compounds/

Emergency and supportive measures: After acute high-intensity inhalation exposure, maintain on open airway, give bronchodilators as needed for wheezing, and observe for 8-12 hours for pulmonary edema. Once airway hyperactivity has been documented, further exposure to isocyanate is contraindicated. Involve public health or OSHA agencies to determine whether other workers are at increased risk through improper workplace controls. /Isocyanates/

For more Antidote and Emergency Treatment (Complete) data for METHYL ISOTHIOCYANATE (6 total), please visit the HSDB record page.

/HUMAN EXPOSURE STUDIES/ Seventy individuals (38 males, 32 females) with a mean age of 32 years (range, 18-67 years; median age, 28 years) were exposed to air, MITC, and/or acetic acid. Between 9 and 16 subjects were examined under each dose/time period combination. Three exposure periods, 14 min, 4 hr and 8 hr were used. In the eight hour test, subjective responses, blink rates and tearing were assessed at 0, 1.5, 3, 3.5, 6 and 8 hr (tearing was not measured at 3.5 hours). Two 15 min rest breaks and a 30 min lunch break were permitted during the 8 hr period. In the four hour test, these same parameters were assessed at 0, 1, 2, 3 and 4 hr (tearing was not measured at 0, 2 and 3 hr). In the 14 min exposure protocol, subjective responses and blink rates were measured at 0, 1, 4 and 14 minutes after the start of exposure. Tearing was measured at 14 min only. Visual acuity and ocular morphology were assessed at the beginning and end of each exposure period. All analyses were performed in a double-blind manner. In the 4 and 8 hr tests, subjects exposed to 0.22 ppm (220 ppb) MITC did not mount a statistically significant irritation response to the test material. A 4 hr exposure to 0.8 ppm (800 ppb) MITC resulted in a statistically significant positive response based on averaging the subjective assessments by the subjects using the Likert scale methodology. In that test, as many as 8 out of 9 subjects exposed under those particular conditions showed a positive response at 1 and 2 hr, the first two time points examined. ... Mean responses at those times, expressed as the percentage of the full Likert scale indicated by the subject, were 25% (+/-14% )and 26% (+/-14%), respectively, compared to 2% (+/-2%) in zero-time untreated controls. ... One hr and 2 hr air-only controls exhibited responses of 6% (+/-9%) and 5% (+/-8%), respectively. By 3 and 4 hr, all 9 subjects appeared to respond positively, with mean responses of 39% (+/-19%) and 39% (+/-26%), respectively. Air-only controls at the latter 2 times were 5% (+/-6%) and 4% (+/-6%), respectively. Shorter exposures to 0.6 ppm did not result in statistically significant increases, though 1 of 9 individuals appeared to respond at 4 and 14 minutes. Exposure to 1.9 ppm or 3.3 ppm MITC resulted in positive subjective responses at 4 and 14 minutes. At 1 minute of exposure, levels as high as 3.3 ppm did not evoke a statistically significant positive response. Blink rate measurements at 0.8 ppm were statistically significantly increased at the 2- and 3- hr time points, with 7 of 9 subjects responding positively. Mean blinks per minute (minus the zero-time rate) were 16 (+/-11) and 14 (+/-13) at those times. Air-only control rates at 2 and 3 hr were 3 (+/-9) and 3 (+/-8) blinks per minute, respectively. Statistical significance was not achieved at 1 and 4 hr, though a positive response was suggested in several individuals. The blink response to 0.6 ppm and 1.9 ppm at 1, 4, and 14 minutes did not indicate positivity. At 3.3 ppm, statistical significance was achieved at 4 and 14 minutes. A strong suggestion of a response was also present at 1 minute, though it was not statistically significant. No statistically positive tearing responses were observed. However, 2 of 9 individuals exposed to 3.3 ppm MITC showed apparently positive responses at 14 minutes (longer exposures were not evaluated at this concentration).

/HUMAN EXPOSURE STUDIES/ Sera of six workers with conclusive evidence for IgE-mediated sensitization to isocyanates were used for evaluation of immunologic cross-reactivities among eight different isocyanate-protein conjugates. In all cases RAST and/or skin-test investigations revealed the presence of IgE antibodies reacting specifically with HSA conjugated with those isocyanates to which workers were exposed as well as with other isocyanates with which they had not been in contact. By the RAST inhibition technique, moderate to strong mutual cross-reactivities between all tested isocyanate-HSA conjugates--even between aromatic and aliphatic ones--could be demonstrated in tests with five sera. The magnitudes of cross-reactivities differed, however, from one patient to another. One serum contained IgE antibodies that were almost completely specific to TDI-HSA; with this serum only weak cross-reactivities with other isocyanate conjugates could be demonstrated. These results indicate the predominance of closely related antigenic determinants in HSA conjugated with different isocyanates. The common antibody-binding regions are obviously recognized to different extents by antibodies of clinically sensitized workers, indicating individual differences in specificities and avidities of antibody populations. Nearly complete lack of IgE binding of ovalbumin-bound TDI in RAST and RAST inhibition indicates carrier-specific antigenicity of isocyanate-protein conjugates. In addition, since unmodified HSA did not bind IgE, antigenic determinants of the conjugates studied should be predominantly formed by the isocyanate-protein bond regions and concurrently by neighboring amino acid residues of the HSA molecule. /Isocyanates/

/SIGNS AND SYMPTOMS/ Strong mucous membrane irritation causes eye, pulmonary, and gastrointestinal tract symptoms. These compounds are potent pulmonary sensitizers which cause bronchospasm, even in patients without prior airway hyperreactivity. Diisocyanate compounds act either as inducers of nonspecific bronchial hyperreactivity or as direct pharmacologic agonists. Isocyanates apparently have the potential to sensitize certain segments of the population. Elevated humoral antibodies (ie, specific IgE antibodies to the p-tolyl determinant but not the diisocyanate conjugate) were detected in sensitized workers, but cell-mediated immunity also may produce hypersensitivity reactions. In the absence of renewed exposure, radioallergosorbent titers may not distinguish sensitive from nonsensitized workers. At high doses, toluene diisocyanate may act directly on bronchial mucosa by interfering with cholinergic and adrenergic mechanisms. /Isocyanates/

/SIGNS AND SYMPTOMS/ Exposure to isocyanates is irritating to the skin, mucous membranes, eyes, and respiratory tract. The most common adverse health outcome associated with isocyanate exposure is asthma due to sensitization; less prevalent are contact dermatitis (both irritant and allergic forms) and hypersensitivity pneumonitis (HP). Contact dermatitis can result in symptoms such as rash, itching, hives, and swelling of the extremities. /Isocyanates/

For more Human Toxicity Excerpts (Complete) data for METHYL ISOTHIOCYANATE (10 total), please visit the HSDB record page.

/LABORATORY ANIMALS: Acute Exposure/ Selected sulfhydryl-reactive pesticides activate mouse liver microsomal glutathione S-transferase (GSTm)... . Maximum activations were as follows: 1315% for N-ethylmaleimide (positive control) at 1 mM, 374% for chloranil at 0.01 mM, 272% for EPTC sulfoxide at 10 mM, 255% for captan at 0.1 mM, 228% for acrolein at 1 mM, and 152% for methyl isothiocyanate at 10 mM.

/LABORATORY ANIMALS: Acute Exposure/ Changes in dermal glutathione status and oxidative stress associated with application of allergenic sesquiterpene lactones and isothiocyanates were studied in mice. Female WSP-mice were administered 5 micromol methyl-isothiocyanate topically. The degree of skin sensitization elicited was determined by the ear swelling assay. Selected mice were killed 12 hours after exposure and the treated skin areas were removed and analyzed for reduced-glutathione (GSH) and glutathione-disulfide (GSSG). Skin microsomal and cytosolic glutathione-S-transferase (GST) activity was also determined. Postmitochondrial fractions prepared from the livers of untreated Wistar-rats were incubated with 0 or 2 micromol methyl-isothiocyanate in the presence of NADPH. The degree of oxidative stress was evaluated by measuring NADPH consumption. /Methyl isothiocyanate did not induce positive responses in the ear swelling test. But methyl-isothiocyanate induced significant increases in skin GSH and GSSG content. Methyl-isothiocyanate significantly increased the rate of hepatic mitochondrial NADPH consumption. The authors conclude that sensitizing sesquiterpene lactones and isothiocyanates can perturb glutathione status and induce oxidative stress in mouse skin.

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ In a 3-month oral gavage toxicity study, male and female Wistar rats received 2, 10, or 40 mg/kg/day MITC (purity unstated). At 40 mg/kg/day toxic effects consisted of undefined stomach lesions, inflammation of the liver, and a slight spermatogenic disorder. The changes were also occasionally noted at 10 mg/kg/day, with slight effects reported at 2 mg/kg/day. Alterations in adrenal and ovary weight were present at 2 mg/kg/day. Details on the adrenal were lacking, but the absolute and relative ovary weights were increased. No histologic adrenal or ovarian changes were reported. Based on the stomach, liver, testes, adrenal, and ovarian abnormalities, the LOEL was 2 mg/kg/day. ...

/LABORATORY ANIMALS: Subchronic or Prechronic Exposure/ In a 3-month oral toxicity study, male and female dd-strain mice were administered 1, 5, or 20 mg/kg/day MITC (purity unstated) by gavage. At 20 mg/kg/day toxic effects included thickening of the forestomach lining, inflammation of the liver and slight disturbance of spermatogenesis with edema of the interstitial area of the testis. These effects were noted occasionally in the 5 mg/kg/day group, and slight changes were present at 1 mg/kg/day. Other changes in the 1 mg/kg/day group included alterations in adrenal and ovary weights. Details on the adrenal gland were lacking, but both absolute and relative ovary weights were significantly decreased at 1 mg/kg/day, although no histologic changes were reported. Based on the changes in the stomach, liver, testis, adrenals, and ovary, the LOEL was 1 mg/kg/day. ...

For more Non-Human Toxicity Excerpts (Complete) data for METHYL ISOTHIOCYANATE (17 total), please visit the HSDB record page.

EC50; Species: Scenedesmus subspicatus (Green Algae); Conditions: freshwater, static; Concentration: 254 ug/L for 96 hr (95% confidence interval: 218-296 ug/L); Effect: population abundance /95.7% pure formulation/

EC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, flow through; Concentration: 55 ug/L for 48 hr; Effect: intoxication, immobilization /95% pure formulation/

LC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 250 mg/L CaCO3, dissolved oxygen >6.5 mg/L; Concentration: 80 ug/L for 14 days (95% confidence interval: 32-100 ug/L) /formulation/

LC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 250 mg/L CaCO3, dissolved oxygen >6.5 mg/L; Concentration: 280 ug/L for 48 hr (95% confidence interval: 180-560 ug/L) /formulation/

For more Ecotoxicity Values (Complete) data for METHYL ISOTHIOCYANATE (10 total), please visit the HSDB record page.

/PLANTS/ Phytotoxic to all green plants.

/FIELD STUDIES/ On July 14, 1991, 72,000 L of the pesticide Metam (active ingredient, methyl isothiocyanate) was accidentally released into the Upper Sacramento River. /It was/ hypothesized that the spill affected streamside microbial communities and that the effects were persistent. To address this hypothesis, ...river soils /were sampled/ a year later from sites above and below the spill as well as from an agricultural area and determined soil carbon dioxide efflux (as a measure of soil respiration) in response to methyl isothiocyanate in controlled-environment microcosms, resulting in estimates of the EC50 and soil degradation rates of methyl isothiocyanate. The soil respiration EC50s for the river soils ranged from 13.2 to 51.4 ug/g methyl isothiocyanate, whereas that of the agricultural soil was 72.2 ug/g. Thus, the soils from the Upper Sacramento River were more sensitive to the toxicologic effects of methyl isothiocyanate than was the agricultural soil. Soils from below the spill site also showed higher (factor two or more) EC50s than soils from reference locations above the spill site. The half-life of methyl isothiocyanate in soils ranged from 2.7 to 6.9 days and was longer by a factor of two in the river soils. These degradation rates are controlled by both biotic (microbial) and abiotic processes. The presence of a microbial community accelerated the degradation rate by a factor of two. The pattern of EC50 data demonstrates that changes in the microbial community in the river soils were persistent a full year after the spill and that the stress elicited responses that were indicative of physiologic accommodation or selection for resistance at the population, species, and/or community level.

EC50; Species: Scenedesmus subspicatus (Green Algae); Conditions: freshwater, static; Concentration: 254 ug/L for 96 hr (95% confidence interval: 218-296 ug/L); Effect: population abundance /95.7% pure formulation/

EC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, flow through; Concentration: 55 ug/L for 48 hr; Effect: intoxication, immobilization /95% pure formulation/

LC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 250 mg/L CaCO3, dissolved oxygen >6.5 mg/L; Concentration: 80 ug/L for 14 days (95% confidence interval: 32-100 ug/L) /formulation/

LC50; Species: Daphnia magna (Water Flea) age <24 hr; Conditions: freshwater, static, 20 °C, pH 8.2, hardness 250 mg/L CaCO3, dissolved oxygen >6.5 mg/L; Concentration: 280 ug/L for 48 hr (95% confidence interval: 180-560 ug/L) /formulation/

For more Ecotoxicity Values (Complete) data for METHYL ISOTHIOCYANATE (10 total), please visit the HSDB record page.

/PLANTS/ Phytotoxic to all green plants.

/FIELD STUDIES/ On July 14, 1991, 72,000 L of the pesticide Metam (active ingredient, methyl isothiocyanate) was accidentally released into the Upper Sacramento River. /It was/ hypothesized that the spill affected streamside microbial communities and that the effects were persistent. To address this hypothesis, ...river soils /were sampled/ a year later from sites above and below the spill as well as from an agricultural area and determined soil carbon dioxide efflux (as a measure of soil respiration) in response to methyl isothiocyanate in controlled-environment microcosms, resulting in estimates of the EC50 and soil degradation rates of methyl isothiocyanate. The soil respiration EC50s for the river soils ranged from 13.2 to 51.4 ug/g methyl isothiocyanate, whereas that of the agricultural soil was 72.2 ug/g. Thus, the soils from the Upper Sacramento River were more sensitive to the toxicologic effects of methyl isothiocyanate than was the agricultural soil. Soils from below the spill site also showed higher (factor two or more) EC50s than soils from reference locations above the spill site. The half-life of methyl isothiocyanate in soils ranged from 2.7 to 6.9 days and was longer by a factor of two in the river soils. These degradation rates are controlled by both biotic (microbial) and abiotic processes. The presence of a microbial community accelerated the degradation rate by a factor of two. The pattern of EC50 data demonstrates that changes in the microbial community in the river soils were persistent a full year after the spill and that the stress elicited responses that were indicative of physiologic accommodation or selection for resistance at the population, species, and/or community level.

Methyl isothiocyanate's production may result in its release to the environment through various waste streams; its use as a multi-purpose soil fumigant for control of nematodes, soil fungi, soil insects, and weed seeds will result in its direct release to the environment. The pesticides metam-sodium and metam-potassium are converted to methyl isothiocyanate in the environment, particularly in the presence of moisture. If released to air, a vapor pressure of 3.54 mm Hg at 25 °C indicates methyl isothiocyanate will exist solely as a vapor in the atmosphere. Vapor-phase methyl isothiocyanate will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 78 days. Methyl isothiocyanate is sensitive to light and therefore may be susceptible to direct photolysis by sunlight. The half-life for gas-phase photolysis of methyl isothiocyanate was 10 hrs in quartz containers. If released to soil, methyl isothiocyanate is expected to have very high mobility based upon Koc values of 3-14.5. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 4.5X10-5 atm-cu m/mole. Methyl isothiocyanate may volatilize from dry soil surfaces based upon its vapor pressure. Using the first order kinetics, the biodegradation half-life in soil was estimated to range from 0.5 to 50 days, suggesting that biodegradation may be an important environmental fate process in soil, depending on conditions. If released into water, methyl isothiocyanate is not expected to adsorb to suspended solids and sediment based upon the Koc values. Utilizing the Japanese MITI test, 0% of the Theoretical BOD was reached in 4 weeks indicating that biodegradation is not an important environmental fate process in water. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 19 hours and 9 days, respectively. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is expected to be an important environmental fate process based upon hydrolysis half-lives in a buffered system of 65 and 178 days at 25 and 0 °C, respectively, and a pH of 7.0. Occupational exposure to methyl isothiocyanate may occur through inhalation of dust and dermal contact with this compound at workplaces where methyl isothiocyanate is produced or used. Monitoring and use data indicate that exposure may be limited to the general population via inhalation of ambient air in areas immediately following agricultural use in nearby produce fields. (SRC)

Methyl isothiocyanate's production may result in its release to the environment through various waste streams; its use as a multi-purpose soil fumigant for control of nematodes, soil fungi, soil insects, and weed seeds(1) will result in its direct release to the environment(SRC). The pesticides metam-sodium and metam-potassium are converted to methyl isothiocyanate in the environment, particularly in the presence of moisture(2).

TERRESTRIAL FATE: Based on a classification scheme(1), a Koc range of 3-14.5(2-5(2) indicates that methyl isothiocyanate is expected to have very high mobility in soil(SRC). Volatilization of methyl isothiocyanate from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 4.5X10-5 atm-cu m/mole(SRC), based upon its vapor pressure, 3.54 mm Hg(6), and water solubility, 7.6X10+3 mg/L(7). Methyl isothiocyanate is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(6). Using the first order kinetics, the biodegradation half-life in soil was estimated to range from 0.5 to 50 days(8) suggesting that biodegradation may be an important environmental fate process in soil, depending on conditions(SRC).

TERRESTRIAL FATE: In damp soil, degradation and evaporation of the bulk of the substance occurs within 3 weeks at 18-20 °C soil temperature, 4 weeks at 6-12 °C, and 8 weeks at 0-6 °C. At the lower temperatures, leaching is more significant and is dependent on soil moisture(1).

AQUATIC FATE: Based on a classification scheme(1), Koc values of 3-14.5(2-5) indicate that methyl isothiocyanate is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(6) based upon an estimated Henry's Law constant of 4.5X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 3.54 mm Hg(7), and water solubility, 7.6X10+3 mg/L(8). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 19 hrs and 9 days, respectively(SRC). According to a classification scheme(9), an estimated BCF of 3(SRC), from its log Kow of 0.94(10) and a regression-derived equation(11), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Hydrolysis half-lives in a buffered system were determined to be 65 and 178 days at 25 and 0 °C, respectively, and a pH of 7.0(12). Utilizing the Japanese MITI test, 0% of the Theoretical BOD was reached in 4 weeks(13) indicating that biodegradation is not an important environmental fate process in water(SRC).

AQUATIC FATE: As a result of a spill on July 14, 1991 into the Sacramento River near Mount Shasta, CA of metam-sodium from seven derailed train cars, methyl isothiocyanate was detected in water and sediment samples along the 68 km river stretch, from spill site to the entrance of Lake Shasta(1). Concentrations ranged from 25 ppm to 15 ppm over the course of 4 days, formed as a result of oxidation of metam-sodium(1).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methyl isothiocyanate, which has a vapor pressure of 3.54 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase methyl isothiocyanate 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 78 days(SRC), calculated from its rate constant of 1.36X10-13 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Methyl isothiocyanate is sensitive to light(4), and therefore may be susceptible to direct photolysis by sunlight(SRC). The half-life for gas-phase photolysis of methyl isothiocyanate was 10 hrs in quartz containers(5).

AEROBIC: In a soil biodegradation study, the biodegradation of methyl isothiocyanate generally followed first order kinetics in soils previously untreated with the compound(1). In soils previously exposed to methyl isothiocyanate, the biodegradation was generally much faster and the biodegradation did not follow first order kinetics(1). Even in soils that were previously untreated with methyl isothiocyanate, an accelerated transformation (which did follow first order kinetics) was observed after an initial period (8-15 days) of first order transformation(1). Using the first order kinetics, the biodegradation half-life was estimated to range from 0.5 to 50 days(2). Generally, the transformation was appreciably faster in soils that have been previously treated with the chemical frequently(2). At or above concentrations of 0.8 mg/L, methyl isothiocyanate inhibited nitrification in the activated sludge process of sewage disposal(2). Methyl isothiocyanate was confirmed to be biodegradable according to a Netherlands study that employed 10 soils under field conditions(3). Soil core samples from Dutch agricultural fields with a 4 year history of methyl isothiocyanate treatment were incubated with the test compound for 1 to 14 days at 20 °C; 50% degradation times ranged from 0.5 to 9 days(3). In the laboratory, it was observed that methyl isothiocyanate biodegradation is influenced by factors such as nursery history, fumigant application rates, and freshness of tested soils(4). Methyl isothiocyanate, applied at 195-780 kg/hectacre and incubated at 22 °C, exhibited half-lives of 3.14-11.20 days in Hayward, WI forest soils; half-lives in 3 Byromville, GA nursery soils ranged from 3.38-4.61 days(4).

AEROBIC: Methyl isothiocyanate, present at 100 mg/L, reached 0% of its theoretical BOD in 4 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test. Degradation metabolites identified included methylamine, 1,3-dimethylthiourea, sulfur, carbon disulfide, 3-methylamino-5-oxa-4-thia-2,7-diaza-2,6-octadiene, 3-methylamino-4,5-dithia-2,7-diaza-2,6-octadiene(1).

The rate constant for the vapor-phase reaction of methyl isothiocyanate with photochemically-produced hydroxyl radicals has been estimated as 1.4X10-13 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 78 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Methyl isothiocyanate is rapidly hydrolyzed by alkalis, more slowly hydrolyzed in acidic and neutral solutions(2). Using conditions representative of the upper Sacramento River system, site of a metam-sodium spill, hydrolysis half-lives in a buffered system were determined to be 65 and 178 days at 25 and 0 °C, respectively, and a pH of 7.0(3); results at pH 10 were 0.7 and 10 days at 25 and 9 °C, respectively, and at pH 4, half-lives of 15 and 67 days at 25 and 0 °C, respectively, were reported(3). Sediment increased the rate to 34 days at 10 °C, pH 7.0(3). The half-life for gas-phase photolysis of methyl isothiocyanate was 10 hrs in quartz containers(4). Under outdoor conditions, nearly half the methyl isothiocyanate was lost in quartz chambers after 29 hrs of continuous exposure, including nighttime, when essentially no compound was lost(4). Using a soil column study that simulated environmental Moroccan conditions (0.84% organic matter, pH 7.6, 12.5% moisture, 4.28% clay, 12.32% loam, 83.41% sand), photodegradation losses were noted as 0, 16.45, 33.98, 63.26% at 1, 2, 4, and 11 days, respectively(5).

An estimated BCF of 3 was calculated in fish for methyl isothiocyanate(SRC), using a log Kow of 0.94(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Koc of methyl isothiocyanate ranges from 3 to 14.5(1-4). According to a classification scheme(5), this Koc range suggests that methyl isothiocyanate is expected to have very high mobility in soil(SRC). Methyl isothiocyanate was shown to leach readily using repacked soil columns; nearly all the applied solution was recovered in the leachate(6). Using a soil column study that simulated environmental Moroccan conditions (0.84% organic matter, pH 7.6, 12.5% moisture, 4.28% clay, 12.32% loam, 83.41% sand), methyl isothiocyanate was shown to concentrate at the 0-40 cm soil layer within 24 hours(7).

The Henry's Law constant for methyl isothiocyanate is estimated as 4.5X10-5 atm-cu m/mole(SRC) derived from its vapor pressure, 3.54 mm Hg(1), and water solubility, 7,600 mg/L(2). This Henry's Law constant indicates that methyl isothiocyanate is expected to volatilize from water surfaces(3). Based on this estimated Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 19 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 9 days(SRC). Methyl isothiocyanate's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). In repacked soil column experiments, volatilization was found to be influenced by gas- and liquid-phase diffusion, the former being influenced by soil water content and soil bulk density(4). In 22 days, 37% of the compound evaporated from a compost soil treated with methyl isothiocyanate(5). Using a soil column study that simulated environmental Moroccan conditions (0.84% organic matter, pH 7.6, 12.5% moisture, 4.28% clay, 12.32% loam, 83.41% sand), methyl isothiocyanate exhibited a half-life of 6.5 days with total volatilization loss at 9%, the later being influenced by soil water contents(6). The potential for volatilization of methyl isothiocyanate from dry soil surfaces may exist(SRC) based upon its vapor pressure(1).

GROUNDWATER: Methyl isothiocyanate was detected in 31 groundwater samples collected from The Netherlands and reported in 1991, at a maximum concentration of 0.42 ug/L(1). The compound was not detected in 14,864 US wells sampled from 1971 through 1991(2).

SURFACE WATER: Methyl isothiocyanate was detected, not quantified in one (River Schussen) of seven rivers and brooks entering Lake Constance in south west Germany; detection dates in this sample were May 21, June 10, and August 8(1). An attributable source could not be identified(1). The compound has been detected, not quantified in Dutch surface water samples(2).

Methyl isothiocyanate was determined as one of the volatile compounds produced by a blue-green algae (Microcyctis aeruginosa) bloom on inland Lake Suwa, Japan(1).

SOURCE DOMINATED: Following injection of metam-sodium into soil in 2 fields in the Netherlands, concentrations of methyl isothiocyanate in downwind air around these fumigated fields were greater than 3 ug/cu m 1 day after fumigation; 7 to 9 days later the concentrations ranged from less than 1.6 to 2.9 ug/cu m(1). Residential expansion into traditionally agricultural areas in South Franklin County, Washington has resulted in increased non-occupational exposure to methyl isothiocyanate following center-pivot chemigation field application of metam-sodium. Air samples were collected between Sept 26, 2005 and Oct 25, 2005; a maximum concentration of 67 ug/cu m within 12 hours of a fall fumigation on October 21, 2005(2). Following application of metam-sodium at 480 L/ha, maximum concentration of methyl isothiocyanate were 11.2 and 7.4 ug/cu m at 10 cm above ground 6-8 hours following application and minimum concentrations were 0.7 and 0.2 ug/cu m observed at 200 ug/cu m 30-35 hrs after chemigated and injected fields, respectively(3).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 1,683 workers are potentially exposed to methyl isothiocyanate in the US(1). The NOES Survey does not include farm workers. Occupational exposure to methyl isothiocyanate may occur through inhalation and dermal contact with this compound at workplaces where methyl isothiocyanate is produced or used(SRC). Since methyl isothiocyanate is produced in moist soil following application of dazomet(2), metam-sodium(3,4), and metam-potassium(4), workers involved in the application of these pesticides are likely to be exposed to methyl isothiocyanate(SRC). Monitoring and use data indicate that exposure may be limited to the general population via inhalation of ambient air in areas immediately following agricultural use in nearby produce fields(SRC).

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

If ... THERE IS NO FIRE, go directly to the Table of Initial Isolation and Protective Action Distances /(see table below)/ ... to obtain initial isolation and protective action distances. IF THERE IS A FIRE, or IF A FIRE IS INVOLVED, go directly to the appropriate guide /(see guide(s) below)/ and use the evacuation information shown under PUBLIC SAFETY.

Table: Table of Initial Isolation and Protective Action Distances for Methyl isothiocyanate [Table#5957]

/GUIDE 131: FLAMMABLE LIQUIDS - TOXIC/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion and poison hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

/GUIDE 131: FLAMMABLE LIQUIDS - TOXIC/ Health: TOXIC; may be fatal if inhaled, ingested or absorbed through skin. Inhalation or contact with some of these materials will irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

/GUIDE 131: FLAMMABLE LIQUIDS - TOXIC/ Public Safety: CALL Emergency Response Telephone Number on Shipping Paper first. If Shipping Paper not available or no answer, refer to appropriate telephone number listed on the inside back cover. As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering.

For more DOT Emergency Guidelines (Complete) data for METHYL ISOTHIOCYANATE (9 total), please visit the HSDB record page.

UN 2477; Methyl isothiocyanate

IMO 6.1; Methyl isothiocyanate

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

Poison Inhalation Hazard Flammable Liquid