UN 1686 — Sodium arsenite, aqueous solution
Placard: Toxic. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1686 is Sodium arsenite, aqueous solution, a toxic arsenic-containing material assigned to ERG Guide 154. The key responder concern is preventing inhalation of dust or fumes and preventing contaminated runoff.
Hazard overview: UN 1686 presents arsenic dust, fume and ingestion hazards. Heating or fire can create toxic arsenic-containing fumes, and dry powder can contaminate clothing, equipment and surfaces.
Response guidance: For a UN 1686 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 154. Establish incident command, isolate the area, stay upwind, prevent dust or vapor exposure, control runoff and choose entry or cleanup actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1686 should emphasize arsenic/heavy-metal dust exposure, contamination control, SCBA use, runoff containment and decontamination. Use ERG 154, SDS and local SOP.
Regulatory context: Sodium arsenite, aqueous solution is regulated as a toxic arsenic/heavy-metal hazardous material. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by compound, concentration, quantity and jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Sodium arsenite, aqueous solution should be stored in tightly closed compatible containers in a secure, cool, dry, well-ventilated toxic-material area away from food, incompatible chemicals, heat and unauthorized access. Prevent dust release, leaks and contaminated runoff.
UN 1686 Quick Details
Common Hazards of UN 1686
- HIGHLY TOXIC arsenic-containing material; may be fatal if inhaled, ingested or absorbed through skin.
- Dust or powder can create a serious inhalation and contamination hazard.
- Avoid skin contact and prevent dust from becoming airborne.
- Fire or heating may produce toxic arsenic-containing fumes.
- Runoff from fire control or spill control may pollute waterways.
- Containers may rupture or fail when heated.
- Specific toxicity and solubility depend on the exact arsenic compound.
Chemical Identity & Physical Properties
Clear to slightly cloudy aqueous solution, colorless to pale straw-colored liquid. Odorless or faint 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
Use positive-pressure SCBA for dust, fumes, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS; avoid all skin contact and contaminated dust.
Isolation & Evacuation
First Actions for a UN 1686 Incident
- CALL 911. Then call the emergency response telephone number on the shipping paper, if available.
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Avoid breathing vapors, fumes, dust or mist and avoid all skin or eye contact.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Avoid creating dust clouds or spreading contaminated liquid, powder, solution, runoff or debris.
- Ventilate closed spaces before entering, but only if properly trained, equipped, monitored and authorized by incident command.
- Isolate the spill or leak area and expand the perimeter if dust, vapor, fire involvement or unknown concentration is present.
- Use ERG Guide 154, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 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.