☣️ UN 1686 • CLASS 6
UN 1686 — Sodium arsenite, aqueous solution
Placard: Toxic. ERG Guide 154. 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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UN 1686 Quick Details
UN 1686
Product name: Sodium arsenite, aqueous solution
DOT Class: 6
Placard type: Toxic
ERG Guide: 154 (check current ERG)
Initial isolation: ERG 154: Initial isolation 25m in all directions; protective action distance 0.3 km downwind daytime, 0.8 km nighttime for small spills
Common Hazards of UN 1686
- TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
- Contact with molten substance may cause severe burns to skin and eyes.
- Avoid any skin contact.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.).
- Corrosives in contact with metals may evolve flammable hydrogen gas.
Chemical Identity & Physical Properties
| Also known as | Sodium metaarseniteArsenous acid sodium saltSodium arsenite solutionPeniteProdalumnol |
| CAS Number | 7784-46-5 |
| Appearance | Clear to slightly cloudy aqueous solution, colorless to pale straw-colored liquid. Odorless or faint garlic-like odor when concentrated. |
| Flash Point | Not applicable (aqueous solution, non-flammable) |
| Boiling Point | Approximately 100C (212F), similar to water depending on concentration |
| Vapor Density | Not applicable (non-volatile aqueous solution) |
| Water Reactivity | Soluble in water; solution itself is stable but highly toxic |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1686
Extinguishing Media
Water spray for fire control acceptable; foam not typically required as solution is non-flammable
PPE Requirements
⚠️ Level B minimum with SCBA; full chemical-resistant suit, butyl rubber gloves; avoid all contact with skin, eyes, and clothing
Isolation & Evacuation
ERG 154: Initial isolation 25m in all directions; protective action distance 0.3 km downwind daytime, 0.8 km nighttime for small spills
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 154).
First Actions for a UN 1686 Incident
- 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 in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters
- 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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📋 Copy & Share Field Card
UN 1686 — Sodium arsenite, aqueous solutionHAZMAT RADIO NOTE — UN 1686
Product: Sodium arsenite, aqueous solution
Class 6 / Toxic / ERG 154
PPE: Level B minimum with SCBA; full chemical-resistant suit, butyl rubber gloves; avoid all contact with skin, eyes, and clothing
ISOLATION: ERG 154: Initial isolation 25m in all directions; protective action distance 0.3 km downwind daytime, 0.8 km nighttime for small spills
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 1686 — Sodium arsenite, aqueous solution
Class: 6 | Placard: Toxic | ERG Guide: 154
Appearance: Clear to slightly cloudy aqueous solution, colorless to pale straw-colored liquid. Odorless or faint garlic-like odor when concentrated.
Water Reactivity: Soluble in water; solution itself is stable but highly toxic
Extinguishing: Water spray for fire control acceptable; foam not typically required as solution is non-flammable
PPE: Level B minimum with SCBA; full chemical-resistant suit, butyl rubber gloves; avoid all contact with skin, eyes, and clothing
Isolation: ERG 154: Initial isolation 25m in all directions; protective action distance 0.3 km downwind daytime, 0.8 km nighttime for small spills
— Key Hazards —
• TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury
• Contact with molten substance may cause severe burns to skin and eyes.
• Avoid any skin contact.
— 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/1686 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1686 Sodium arsenite, aqueous solution Cls6 ERG154 | allfirefighter.com/hazmat/un/1686SMS / 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/1686
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Frequently Asked Questions about UN 1686
TOXIC and/or CORROSIVE; inhalation, ingestion or skin contact with material may cause severe injury Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause environmental Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Corrosives in contact with metals may evolve flammable hydrogen gas.
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 B minimum with SCBA; full chemical-resistant suit, butyl rubber gloves; avoid all contact with skin, eyes, and clothing
Water reactivity: Soluble in water; solution itself is stable but highly toxic. Recommended extinguishing: Water spray for fire control acceptable; foam not typically required as solution is non-flammable.
ERG Guide 154 recommendation: ERG 154: Initial isolation 25m in all directions; protective action distance 0.3 km downwind daytime, 0.8 km nighttime for small spills
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 154 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.