☣️ UN 1691 • CLASS 6

UN 1691 — Strontium arsenite

Placard: Toxic. ERG Guide 151. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.

🚒☣️
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.

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.

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UN 1691 Quick Details

UN 1691
Product name: Strontium arsenite
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill 25m minimum; downwind evacuation 100m during day, 300m at night; larger distances if involved in fire

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 asStrontium arseniteArsenous acid strontium saltStrontium metaarsenite
CAS Number14844-70-5
AppearanceWhite to grayish-white crystalline powder or solid. Odorless. Stable at room temperature.
Flash PointNot applicable (non-combustible inorganic solid)
Boiling PointNot applicable (decomposes at high temperature)
Vapor DensityNot applicable (solid with negligible vapor pressure)
Water ReactivitySlightly soluble in water; no violent reaction but releases toxic arsenic compounds
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.

Fireground Response Guidance — UN 1691

Extinguishing Media

Water spray, dry chemical, CO2 suitable for surrounding fire; material itself non-combustible

PPE Requirements

⚠️ Level A recommended for spill response; SCBA required; full chemical-resistant suit to prevent any skin contact

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

ERG 151: isolate spill 25m minimum; downwind evacuation 100m during day, 300m at night; larger distances if involved in fire
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).

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
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📋 Copy & Share Field Card

UN 1691 — Strontium arsenite
HAZMAT RADIO NOTE — UN 1691 Product: Strontium arsenite Class 6 / Toxic / ERG 151 PPE: Level A recommended for spill response; SCBA required; full chemical-resistant suit to prevent any skin contact ISOLATION: ERG 151: isolate spill 25m minimum; downwind evacuation 100m during day, 300m at night; larger distances if involved in fire ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO

Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.

SMS WhatsApp
=== IC HAZMAT BRIEFING === UN 1691 — Strontium arsenite Class: 6 | Placard: Toxic | ERG Guide: 151 Appearance: White to grayish-white crystalline powder or solid. Odorless. Stable at room temperature. Water Reactivity: Slightly soluble in water; no violent reaction but releases toxic arsenic compounds Extinguishing: Water spray, dry chemical, CO2 suitable for surrounding fire; material itself non-combustible PPE: Level A recommended for spill response; SCBA required; full chemical-resistant suit to prevent any skin contact Isolation: ERG 151: isolate spill 25m minimum; downwind evacuation 100m during day, 300m at night; larger distances if involved in fire — Key Hazards — • 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. — First Actions — • 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. SOURCE: allfirefighter.com/hazmat/un/1691 | Always use current ERG + SOP/SOGIC BRIEFING

Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief.

SMS (short)
UN1691 Strontium arsenite Cls6 ERG151 | ERG 151: isolate spill 25m minimum; downwind evacuation 100m during day, 300m at | allfirefighter.com/hazmat/un/1691SMS / 160 CHAR

Use for: Quick text to command or incoming units. Fits in a single SMS.

⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/strontium-arsenite-un-1691

Related UN Numbers in Class 6

Discovery block for training / quick reference. Always consult the current ERG + your SOP/SOG for operations.
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Frequently Asked Questions about UN 1691

Strontium arsenite is a non-combustible inorganic solid with no flash point, though it can emit toxic arsenic-containing gases if exposed to an external fire.

Level A PPE including a fully encapsulating chemical-resistant suit and SCBA is mandatory because even brief skin contact with strontium arsenite can result in fatal arsenic poisoning.

ERG Guide 151 specifies a minimum 25-meter isolation radius around the spill, with protective action evacuation extending 100 meters downwind during the day and 300 meters at night.

Exposure to strontium arsenite can cause acute arsenite poisoning with symptoms including severe gastrointestinal distress, cardiovascular collapse, peripheral neuropathy, and death if not treated promptly.

Strontium arsenite must be stored in a cool, dry, well-ventilated area in tightly sealed corrosion-resistant containers, segregated from food, water sources, and incompatible oxidizers, with restricted access due to its extreme toxicity.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.