UN 1686 — Sodium arsenite, aqueous solution
Placard: Toxic. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Sodium arsenite, aqueous solution is a toxic and corrosive substance that can cause severe injury if inhaled, ingested or skin contact with material. It is a clear to slightly cloudy aqueous solution, colorless to pale straw-colored liquid that is odorless or faintly has a garlic-like odor when concentrated.
Hazard overview: Sodium arsenite, aqueous solution is toxic and corrosive and can cause severe injury if inhaled, ingested or skin contact with material. Contact with molten substance may cause severe burns to skin and eyes.
Response guidance: In case of emergency, use water spray for fire control and avoid all contact with skin, eyes, and clothing. Wear Level B minimum personal protective equipment (PPE) including a self-contained breathing apparatus (SCBA) and butyl rubber gloves.
UN 1686 Quick Details
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
Sodium arsenite, aqueous solution is a clear to slightly cloudy aqueous solution, colorless to pale straw-colored liquid that is odorless or faintly has a garlic-like odor when concentrated.
| 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 |
Fireground Response Guidance — UN 1686
Extinguishing Media
PPE Requirements
Wear Level B minimum personal protective equipment (PPE) including a self-contained breathing apparatus (SCBA) and butyl rubber gloves.
Isolation & Evacuation
First Actions for a UN 1686 Incident
- 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
📋 Copy & Share Field Card
UN 1686 — Sodium arsenite, aqueous solutionUse for: Quick radio or face-to-face size-up. Short, structured, field-ready.
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.
Use for: Quick text to command or incoming units. Fits in a single SMS.