☣️ UN 2477 • CLASS 6
Methyl isothiocyanate
Placard: Toxic. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 2477
Class: 6
Placard type: Toxic
ERG: Guide 131 (check current ERG)
Isolation: ERG 131: Isolate spill 50m all directions; for large spills isolate 800m downwind; evacuate immediate area if tank/container involved in fire
Chemical & Response Details
| Also known as | MITCMethyl mustard oilIsothiocyanatomethaneMethylisothiocyanateMethanisothiocyanate |
| CAS Number | 556-61-6 |
| Appearance | Colorless to pale yellow liquid with a pungent, irritating odor. May have a sharp, mustard-like or lachrymatory smell at room temperature. |
| Flash Point | 32°C (90°F) |
| Boiling Point | 119°C (246°F) |
| Vapor Density | 2.5 (heavier than air) |
| Water Reactivity | Slowly decomposes in water; not violently reactive but produces toxic vapors |
| Extinguishing | Alcohol-resistant foam, CO2, dry chemical; water spray for cooling containers only |
| PPE | ⚠️ Level A or B minimum; SCBA mandatory; full chemical protective suit required; avoid all skin and eye contact |
| Isolation | ERG 131: Isolate spill 50m all directions; for large spills isolate 800m downwind; evacuate immediate area if tank/container involved in fire |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- 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.
- Methyl chloroacetate (UN2295) is an eye irritant/lachrymator (causes flow of tears).
- Fire will produce irritating, corrosive and/or toxic gases.
- Vapors may cause dizziness or asphyxiation, especially when in closed or confined areas.
- Runoff from fire control or dilution water may cause environmental contamination.
- HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.
- Vapors may form explosive mixtures with air.
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Ventilate closed spaces before entering, but only if properly trained and equipped.
- 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
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UN 2477 — Methyl isothiocyanate HAZMAT RADIO NOTE — UN 2477
Product: Methyl isothiocyanate
Class 6 / Toxic / ERG 131
PPE: Level A or B minimum; SCBA mandatory; full chemical protective suit required; avoid all skin and eye contact
ISOLATION: ERG 131: Isolate spill 50m all directions; for large spills isolate 800m downwind; evacuate immediate area if tank/container involved in fire
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 2477 — Methyl isothiocyanate
Class: 6 | Placard: Toxic | ERG Guide: 131
Appearance: Colorless to pale yellow liquid with a pungent, irritating odor. May have a sharp, mustard-like or lachrymatory smell at room temperature.
Water Reactivity: Slowly decomposes in water; not violently reactive but produces toxic vapors
Extinguishing: Alcohol-resistant foam, CO2, dry chemical; water spray for cooling containers only
PPE: Level A or B minimum; SCBA mandatory; full chemical protective suit required; avoid all skin and eye contact
Isolation: ERG 131: Isolate spill 50m all directions; for large spills isolate 800m downwind; evacuate immediate area if tank/container involved in fire
— Key Hazards —
• 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.
• Methyl chloroacetate (UN2295) is an eye irritant/lachrymator (causes flow of tears).
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Ventilate closed spaces before entering, but only if properly trained and equipped.
SOURCE: allfirefighter.com/hazmat/un/2477 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN2477 Methyl isothiocyanate Cls6 ERG131 | ERG 131: Isolate spill 50m all directions; for large spills isolate 800m downwin | allfirefighter.com/hazmat/un/2477SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/2477
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FAQ
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. Methyl chloroacetate (UN2295) is an eye irritant/lachrymator (causes flow of tears). Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or asphyxiation, especially when in closed or confined areas. Runoff from fire control or dilution water may cause environmental contamination. HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level A or B minimum; SCBA mandatory; full chemical protective suit required; avoid all skin and eye contact
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 131 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.