UN 1685 — Sodium arsenate
Placard: Toxic. ERG Guide 151. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1685 is Sodium arsenate, a toxic arsenic-containing material assigned to ERG Guide 151. The key responder concern is preventing inhalation of dust or fumes and preventing contaminated runoff.
Hazard overview: UN 1685 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 1685 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 151. 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 1685 should emphasize arsenic/heavy-metal dust exposure, contamination control, SCBA use, runoff containment and decontamination. Use ERG 151, SDS and local SOP.
Regulatory context: Sodium arsenate 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 arsenate 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 1685 Quick Details
Common Hazards of UN 1685
- 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
White or colorless crystalline powder or granular solid. Odorless. Hygroscopic, readily absorbs moisture from air.
| Also known as | Disodium arsenateArsenate of sodaDisodium hydrogen arsenateSodium acid arsenate |
| CAS Number | 7778-43-0 |
| Appearance | White or colorless crystalline powder or granular solid. Odorless. Hygroscopic, readily absorbs moisture from air. |
| Flash Point | Not applicable (non-flammable inorganic solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water, no significant reaction. Forms toxic arsenate solutions. |
Fireground Response Guidance — UN 1685
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 1685 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 151, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1685 — Sodium arsenateUse 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.