☣️ UN 1622 • CLASS 6

UN 1622 — Magnesium arsenate

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

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⚠️ 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 1622 is Magnesium arsenate, a toxic arsenic-containing material assigned to ERG Guide 151. The key responder concern is preventing inhalation of dust or fumes and preventing contaminated runoff.

Hazard overview: UN 1622 presents arsenic dust, fume and ingestion hazards. Heating or fire can create toxic arsenic-containing fumes, and dry powder can contaminate clothing, equipment and surfaces.

Response guidance: For a UN 1622 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 151. 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 1622 should emphasize arsenic/heavy-metal dust exposure, contamination control, SCBA use, runoff containment and decontamination. Common errors include spreading dry powder and treating nonflammable toxic solids as low risk. Use ERG 151, SDS and local SOP.

Regulatory context: Magnesium arsenate is regulated as a toxic arsenic/heavy-metal 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: Magnesium arsenate should be stored in tightly closed compatible containers in a secure, cool, dry, well-ventilated toxic-material area away from food, incompatible chemicals, heat and unauthorized access. Prevent dust release, leaks and contaminated runoff.

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UN 1622 Quick Details

UN 1622
Product name: Magnesium arsenate
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill 25m all directions; isolate 50m if large spill; evacuate immediate area and downwind if airborne powder suspected

Common Hazards of UN 1622

  • HIGHLY TOXIC arsenic-containing material; may be fatal if inhaled, ingested or absorbed through skin.
  • Dust or powder can create a serious inhalation and contamination hazard.
  • Avoid skin contact and prevent dust from becoming airborne.
  • Fire or heating may produce toxic arsenic-containing fumes.
  • Runoff from fire control or spill control may pollute waterways.
  • Containers may rupture or fail when heated.
  • Specific toxicity and solubility depend on the exact arsenic compound.

Chemical Identity & Physical Properties

White or grayish-white odorless powder or crystalline solid at room temperature. May appear as granules or lumps.

Also known asTrimagnesium diarsenateMagnesium arsenate tribasicArsenate of magnesiumMagnesium salt of arsenic acid
CAS Number7784-36-3
AppearanceWhite or grayish-white odorless powder or crystalline solid at room temperature. May appear as granules or lumps.
Flash PointNot applicable (inorganic solid, non-flammable)
Boiling PointNot applicable (decomposes before boiling)
Vapor DensityNot applicable (solid with negligible vapor pressure)
Water ReactivitySlightly soluble in water; no violent reaction but may release toxic arsenic compounds over time
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.

Fireground Response Guidance — UN 1622

Extinguishing Media

Use extinguishing agents appropriate for the surrounding fire and SDS. Water spray may cool containers or reduce dust only when runoff can be controlled as toxic contamination.

PPE Requirements

⚠️ Level B minimum; SCBA mandatory; full chemical-resistant suit required; avoid all skin contact due to extreme toxicity

Use positive-pressure SCBA for dust, 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

ERG 151: isolate spill 25m all directions; isolate 50m if large spill; evacuate immediate area and downwind if airborne powder suspected
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).

First Actions for a UN 1622 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.
  • Avoid creating dust clouds or spreading contaminated powder, solution, runoff or debris.
  • 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 dust, vapor, fire involvement or unknown concentration is present.
  • Use ERG Guide 151, shipping papers, SDS, air monitoring and incident command for protective actions.
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📋 Copy & Share Field Card

UN 1622 — Magnesium arsenate
HAZMAT RADIO NOTE — UN 1622 Product: Magnesium arsenate Class 6 / Toxic / ERG 151 PPE: Level B minimum; SCBA mandatory; full chemical-resistant suit required; avoid all skin contact due to extreme toxicity ISOLATION: ERG 151: isolate spill 25m all directions; isolate 50m if large spill; evacuate immediate area and downwind if airborne powder suspected 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 1622 — Magnesium arsenate Class: 6 | Placard: Toxic | ERG Guide: 151 Appearance: White or grayish-white odorless powder or crystalline solid at room temperature. May appear as granules or lumps. Water Reactivity: Slightly soluble in water; no violent reaction but may release toxic arsenic compounds over time Extinguishing: Use extinguishing agents appropriate for the surrounding fire and SDS. Water spray may cool containers or reduce dust only when runoff can be controlled as toxic contamination. PPE: Level B minimum; SCBA mandatory; full chemical-resistant suit required; avoid all skin contact due to extreme toxicity Isolation: ERG 151: isolate spill 25m all directions; isolate 50m if large spill; evacuate immediate area and downwind if airborne powder suspected — Key Hazards — • HIGHLY TOXIC arsenic-containing material; may be fatal if inhaled, ingested or absorbed through skin. • Dust or powder can create a serious inhalation and contamination hazard. • Avoid skin contact and prevent dust from becoming airborne. — First Actions — • 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. SOURCE: allfirefighter.com/hazmat/un/magnesium-arsenate-un-1622 | Always use current ERG + SOP/SOGIC BRIEFING

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

SMS (short)
UN1622 Magnesium arsenate Cls6 ERG151 | allfirefighter.com/hazmat/un/magnesium-arsenate-un-1622SMS / 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/magnesium-arsenate-un-1622

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 1622

UN 1622 is Magnesium arsenate, a hazardous material assigned to ERG Guide 151.

No. It is generally not flammable, but fire or heating can produce toxic arsenic-containing fumes.

ERG Guide 151 applies to UN 1622 for initial isolation, protective actions and first response guidance.

UN 1622 presents arsenic dust, fume and ingestion hazards. Heating or fire can create toxic arsenic-containing fumes, and dry powder can contaminate clothing, equipment and surfaces.

Use positive-pressure SCBA for dust, 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.

Arsenic or heavy-metal dust can contaminate clothing, equipment and surfaces and may be dangerous by inhalation or ingestion.
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.