UN 1553 — Arsenic acid, liquid
Placard: Toxic. ERG Guide 154. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1553 is Arsenic acid, liquid, a toxic corrosive arsenic material assigned to ERG Guide 154. It can injure responders through skin or eye contact, inhaled mist/dust and contaminated runoff.
Hazard overview: UN 1553 presents toxic arsenic exposure and corrosive acid hazards. Fire, heating or runoff may spread arsenic contamination, so responders should isolate the area and control drains and waterways.
Response guidance: For a UN 1553 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 1553 should emphasize arsenic dust/fume exposure, contamination control, SCBA use, runoff containment and decontamination. Common errors include treating nonflammable toxic solids as low risk and spreading dust during cleanup. Use ERG 154, SDS and local SOP.
Regulatory context: Arsenic acid, liquid is regulated as a toxic arsenic 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: Arsenic acid, liquid should be stored in compatible corrosion-resistant containers in a secure, cool, well-ventilated toxic/corrosive area away from incompatible metals, reducing agents, bases and unauthorized access. Secondary containment and runoff control should follow SDS.
UN 1553 Quick Details
Common Hazards of UN 1553
- TOXIC and CORROSIVE arsenic acid; inhalation, ingestion or skin contact may cause severe injury.
- Dust, mist or solution contact may burn or irritate eyes, skin and respiratory tissue.
- May form toxic arsenic-containing runoff or residues.
- Some arsenic acid materials may support oxidation or react with incompatible metals or reducing agents.
- Fire may produce irritating, corrosive and/or toxic gases.
- Containers may rupture or fail when heated.
- Avoid all skin contact and prevent contaminated runoff from entering waterways.
Chemical Identity & Physical Properties
Clear to slightly colored aqueous solution. Odorless or slight acidic odor. Corrosive liquid at room temperature.
| Also known as | Orthoarsenic acidArsenic(V) acidArsenic pentoxide hydrate solutionArsenate solution |
| CAS Number | 7778-39-4 |
| Appearance | Clear to slightly colored aqueous solution. Odorless or slight acidic odor. Corrosive liquid at room temperature. |
| Flash Point | Not applicable (aqueous solution) |
| Boiling Point | Approximately 100C (212F) for aqueous solutions |
| Vapor Density | Not applicable (aqueous solution) |
| Water Reactivity | Dissolves readily in water; already an aqueous solution |
Fireground Response Guidance — UN 1553
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, mist, 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 1553 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.
- 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 vapor, dust, 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 1553 — Arsenic acid, liquidUse 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.