UN 1691 — Strontium arsenite
Placard: Toxic. ERG Guide 151. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1691, Strontium Arsenite, is an inorganic arsenic salt classified as a Class 6 toxic substance capable of causing fatal poisoning through inhalation, ingestion, or dermal absorption. It presents as a white to grayish-white crystalline powder and poses severe systemic toxicity hazards during transport incidents or accidental release.
Hazard overview: Strontium arsenite releases toxic arsenic compounds upon contact with water and can generate irritating or corrosive gases if involved in fire, creating both acute and environmental hazards. Even minimal skin contact or dust inhalation represents a life-threatening exposure pathway due to the potent systemic toxicity of inorganic arsenite compounds.
Response guidance: First responders should immediately isolate the spill area to a minimum of 25 meters and initiate downwind evacuation of 100 meters during daylight or 300 meters at night per ERG Guide 151. Avoid all direct contact with the material; contain runoff to prevent arsenic contamination of waterways and notify environmental authorities.
UN 1691 Quick Details
Common Hazards of UN 1691
- Highly toxic, may be fatal if inhaled, ingested or absorbed through skin.
- 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
- Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive
- Containers may explode when heated.
- Runoff may pollute waterways.
Chemical Identity & Physical Properties
Strontium arsenite is an odorless, white to grayish-white crystalline solid that is slightly soluble in water and chemically stable under normal ambient conditions.
| Also known as | Strontium arseniteArsenous acid strontium saltStrontium metaarsenite |
| CAS Number | 14844-70-5 |
| Appearance | White to grayish-white crystalline powder or solid. Odorless. Stable at room temperature. |
| Flash Point | Not applicable (non-combustible inorganic solid) |
| Boiling Point | Not applicable (decomposes at high temperature) |
| Vapor Density | Not applicable (solid with negligible vapor pressure) |
| Water Reactivity | Slightly soluble in water; no violent reaction but releases toxic arsenic compounds |
Fireground Response Guidance — UN 1691
Extinguishing Media
PPE Requirements
Level A protection with a supplied-air SCBA and a fully encapsulating chemical-resistant suit is required for any spill response to prevent fatal arsenic absorption through skin or lungs.
Isolation & Evacuation
First Actions for a UN 1691 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 1691 — Strontium arseniteUse 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.