UN 1560 — Arsenic trichloride
Placard: Toxic. ERG Guide 157. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1560 is Arsenic trichloride, a highly toxic and corrosive arsenic halide assigned to ERG Guide 157. It fumes in moist air and can release corrosive hydrogen halide fumes plus toxic arsenic contamination.
Hazard overview: UN 1560 presents toxic arsenic exposure, corrosive fume and water-reactivity hazards. Water contact can generate heat and dense toxic/corrosive fumes; responders should keep runoff controlled and avoid direct contact.
Response guidance: For a UN 1560 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 157. 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 1560 should emphasize water-reactive toxic/corrosive fumes, arsenic contamination, air monitoring, dry-agent selection and decontamination. Common errors include applying water directly and entering fuming areas without SCBA. Use ERG 157, SDS and hazmat SOP.
Regulatory context: Arsenic trichloride 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 trichloride should be stored in tightly closed compatible containers in a cool, dry, well-ventilated secure area away from water, moisture, acids/bases where incompatible, oxidizers and heat. Protect containers from corrosion, leaks and unauthorized access.
UN 1560 Quick Details
Common Hazards of UN 1560
- HIGHLY TOXIC and CORROSIVE; inhalation, ingestion or skin contact may cause severe or fatal injury.
- Reacts with water or moist air to release corrosive hydrogen halide fumes and toxic arsenic compounds.
- Reaction with water may generate heat and dense irritating fumes.
- Vapors or fumes are heavier than air and may collect in low or confined areas.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may spread toxic and corrosive contamination.
- Containers may rupture or fail when heated.
Chemical Identity & Physical Properties
Colorless to pale yellow oily liquid with a pungent, acrid odor. Fumes in moist air forming white clouds of hydrochloric acid and arsenic trioxide.
| Also known as | Arsenous trichlorideArsenous chlorideButter of arsenicFuming liquid arsenic |
| CAS Number | 7784-34-1 |
| Appearance | Colorless to pale yellow oily liquid with a pungent, acrid odor. Fumes in moist air forming white clouds of hydrochloric acid and arsenic trioxide. |
| Flash Point | Not applicable (non-flammable liquid) |
| Boiling Point | 130C (266F) |
| Vapor Density | 7.0 (much heavier than air) |
| Water Reactivity | Reacts violently with water producing toxic and corrosive hydrogen chloride gas and arsenic acid; generates significant heat |
Fireground Response Guidance — UN 1560
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical-resistant protective clothing for vapor, fume, liquid or unknown exposure. Level A may be needed for close entry because both toxic arsenic and corrosive hydrogen halide fumes are possible.
Isolation & Evacuation
First Actions for a UN 1560 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.
- Keep water and moisture away from the released material unless incident command confirms a compatible cooling or control use.
- 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 157, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1560 — Arsenic trichlorideUse 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.