UN 1558 — Arsenic
Placard: Toxic. ERG Guide 152. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
Arsenic is a highly toxic substance that can be fatal if inhaled, ingested or absorbed through skin. It is a brittle crystalline solid at room temperature and may appear as a black or yellow powder depending on form.
Hazard overview: Highly toxic, may be fatal if inhaled, ingested or absorbed through skin. Contact with molten substance may cause severe burns to skin and eyes.
Response guidance: Use Level A PPE and isolate spill area at least 25m in all directions. For large spills, isolate 50m and consider evacuation of 300m downwind.
UN 1558 Quick Details
Common Hazards of UN 1558
- Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
- 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
- Combustible material: may burn but does not ignite readily.
- Containers may explode when heated.
- Those substances designated with a (P) may polymerize explosively when heated or involved in a fire.
Chemical Identity & Physical Properties
Steel-grey or tin-white, odorless, brittle crystalline solid at room temperature. May appear as a black or yellow powder depending on form.
| Also known as | Metallic arsenicArsenic metalGrey arsenicElemental arsenic |
| CAS Number | 7440-38-2 |
| Appearance | Steel-grey or tin-white, odorless, brittle crystalline solid at room temperature. May appear as a black or yellow powder depending on form. |
| Flash Point | Not applicable (non-combustible solid) |
| Boiling Point | 613C (1135F) - sublimes without melting |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | No significant reaction with water under normal conditions |
Fireground Response Guidance — UN 1558
Extinguishing Media
PPE Requirements
Level A required for spill response; full-face SCBA, chemical-resistant suit; highly toxic by all routes of exposure
Isolation & Evacuation
First Actions for a UN 1558 Incident
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- 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 1558 — ArsenicUse 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.