☣️ UN 1688 • CLASS 6
UN 1688 — Sodium cacodylate
Placard: Toxic. ERG Guide 152. 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.
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UN 1688 Quick Details
UN 1688
Product name: Sodium cacodylate
DOT Class: 6
Placard type: Toxic
ERG Guide: 152 (check current ERG)
Initial isolation: ERG 152: Initial isolation 25m in all directions; protective action distance 150m downwind during spill in day, 300m at night. No evacuation for small spills with proper containment.
Common Hazards of UN 1688
- 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
| Also known as | Sodium dimethylarsinateDimethylarsinic acid sodium saltCacodylic acid sodium saltHydroxydimethylarsine oxide sodium salt |
| CAS Number | 124-65-2 |
| Appearance | White to off-white crystalline powder or solid. Odorless or slight characteristic odor. Hygroscopic, absorbs moisture from air. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Decomposes before boiling |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Soluble in water with no violent reaction; aqueous solutions are weakly alkaline |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Fireground Response Guidance — UN 1688
Extinguishing Media
Water spray, dry chemical, CO2, or sand may be used for firefighting
PPE Requirements
⚠️ Level B minimum with full-face respirator; Level A if inhalation hazard is severe. Butyl or nitrile gloves, chemical-resistant suit, SCBA required in confined spaces or high exposure scenarios.
Isolation & Evacuation
ERG 152: Initial isolation 25m in all directions; protective action distance 150m downwind during spill in day, 300m at night. No evacuation for small spills with proper containment.
Always confirm protective actions with the current edition of the Emergency Response Guidebook (ERG Guide 152).
First Actions for a UN 1688 Incident
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- 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 1688 — Sodium cacodylateHAZMAT RADIO NOTE — UN 1688
Product: Sodium cacodylate
Class 6 / Toxic / ERG 152
PPE: Level B minimum with full-face respirator; Level A if inhalation hazard is severe. Butyl or nitrile gloves, chemical-resistant suit, SCBA required in confined spaces or high exposure scenarios.
ISOLATION: ERG 152: Initial isolation 25m in all directions; protective action distance 150m downwind during spill in day, 300m at night. No evacuation for small spills with proper containment.
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 1688 — Sodium cacodylate
Class: 6 | Placard: Toxic | ERG Guide: 152
Appearance: White to off-white crystalline powder or solid. Odorless or slight characteristic odor. Hygroscopic, absorbs moisture from air.
Water Reactivity: Soluble in water with no violent reaction; aqueous solutions are weakly alkaline
Extinguishing: Water spray, dry chemical, CO2, or sand may be used for firefighting
PPE: Level B minimum with full-face respirator; Level A if inhalation hazard is severe. Butyl or nitrile gloves, chemical-resistant suit, SCBA required in confined spaces or high exposure scenarios.
Isolation: ERG 152: Initial isolation 25m in all directions; protective action distance 150m downwind during spill in day, 300m at night. No evacuation for small spills with proper containment.
— Key Hazards —
• 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.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• 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
SOURCE: allfirefighter.com/hazmat/un/1688 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN1688 Sodium cacodylate Cls6 ERG152 | ERG 152: Initial isolation 25m in all directions; protective action distance 150 | allfirefighter.com/hazmat/un/1688SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions.
Page: https://allfirefighter.com/hazmat/un/1688
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Frequently Asked Questions about UN 1688
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.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum with full-face respirator; Level A if inhalation hazard is severe. Butyl or nitrile gloves, chemical-resistant suit, SCBA required in confined spaces or high exposure scenarios.
Water reactivity: Soluble in water with no violent reaction; aqueous solutions are weakly alkaline. Recommended extinguishing: Water spray, dry chemical, CO2, or sand may be used for firefighting.
ERG Guide 152 recommendation: ERG 152: Initial isolation 25m in all directions; protective action distance 150m downwind during spill in day, 300m at night. No evacuation for small spills with proper containment.
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 152 and your department SOP/SOG for incident-specific protective actions.
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.