☣️ UN 1621 • CLASS 6

UN 1621 — London purple

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 1621 is London purple, a toxic arsenic and heavy-metal material assigned to ERG Guide 151. The main responder concern is preventing inhalation of dust and controlling contaminated runoff.

Hazard overview: UN 1621 presents arsenic plus heavy-metal dust, fume and runoff hazards. Dry powder can contaminate clothing and equipment, and heating may produce toxic metal-containing fumes.

Response guidance: For a UN 1621 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 1621 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: London purple 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: London purple 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 1621 Quick Details

UN 1621
Product name: London purple
DOT Class: 6
Placard type: Toxic
ERG Guide: 151 (check current ERG)
Initial isolation: ERG 151: isolate spill 25m all directions; if large spill isolate 50m; evacuate downwind areas if airborne

Common Hazards of UN 1621

  • HIGHLY TOXIC arsenic and heavy-metal material; may be fatal if inhaled, ingested or absorbed through skin.
  • Dust or powder can create serious inhalation and contamination hazards.
  • Lead or mercury components may add persistent toxic contamination to surfaces, runoff and equipment.
  • Avoid skin contact and prevent dust from becoming airborne.
  • Fire or heating may produce toxic arsenic, lead or mercury fumes depending on the compound.
  • Runoff from fire control or spill control may pollute waterways.
  • Specific solubility and toxicity should be verified from SDS and shipping papers.

Chemical Identity & Physical Properties

Purple to violet-colored powder or crystalline solid. Odorless to slight metallic odor. Solid at room temperature.

Also known asArsenite of limeCalcium arseniteLondon purple insecticideArsenical dustPurple dye
CAS Number8028-73-7
AppearancePurple to violet-colored powder or crystalline solid. Odorless to slight metallic odor. Solid at room temperature.
Flash PointNot applicable (non-combustible solid)
Boiling PointNot applicable (decomposes before boiling)
Vapor DensityNot applicable (solid)
Water ReactivitySlowly soluble in water, may release toxic arsenic compounds
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.

Fireground Response Guidance — UN 1621

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 A or B minimum; full-face SCBA required; chemical-resistant suit; avoid skin contact completely

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; if large spill isolate 50m; evacuate downwind areas if airborne
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 151).

First Actions for a UN 1621 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 1621 — London purple
HAZMAT RADIO NOTE — UN 1621 Product: London purple Class 6 / Toxic / ERG 151 PPE: Level A or B minimum; full-face SCBA required; chemical-resistant suit; avoid skin contact completely ISOLATION: ERG 151: isolate spill 25m all directions; if large spill isolate 50m; evacuate downwind areas if airborne 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 1621 — London purple Class: 6 | Placard: Toxic | ERG Guide: 151 Appearance: Purple to violet-colored powder or crystalline solid. Odorless to slight metallic odor. Solid at room temperature. Water Reactivity: Slowly soluble in water, may release toxic arsenic compounds 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 A or B minimum; full-face SCBA required; chemical-resistant suit; avoid skin contact completely Isolation: ERG 151: isolate spill 25m all directions; if large spill isolate 50m; evacuate downwind areas if airborne — Key Hazards — • HIGHLY TOXIC arsenic and heavy-metal material; may be fatal if inhaled, ingested or absorbed through skin. • Dust or powder can create serious inhalation and contamination hazards. • Lead or mercury components may add persistent toxic contamination to surfaces, runoff and equipment. — 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/london-purple-un-1621 | Always use current ERG + SOP/SOGIC BRIEFING

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

SMS (short)
UN1621 London purple Cls6 ERG151 | allfirefighter.com/hazmat/un/london-purple-un-1621SMS / 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/london-purple-un-1621

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 1621

UN 1621 is London purple, a hazardous material assigned to ERG Guide 151.

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

ERG Guide 151 applies to UN 1621 for initial isolation, protective actions and first response guidance.

UN 1621 presents arsenic plus heavy-metal dust, fume and runoff hazards. Dry powder can contaminate clothing and equipment, and heating may produce toxic metal-containing fumes.

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.