UN 1704 — Tetraethyl dithiopyrophosphate
Placard: Toxic. ERG Guide 153. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1704 is Tetraethyl dithiopyrophosphate, a highly toxic organophosphate liquid assigned to ERG Guide 153. Skin absorption is a major concern, and exposed responders may need medical coordination for cholinesterase inhibitor effects.
Hazard overview: UN 1704 presents organophosphate poisoning, skin absorption and contaminated-runoff hazards. Fire or decomposition may produce phosphorus/sulfur-containing toxic gases.
Response guidance: For a UN 1704 incident, responders should verify the product with shipping papers, package markings, SDS and ERG Guide 153. Establish incident command, isolate the area, stay upwind, prevent dust, vapor or aerosol exposure, control runoff and choose entry or cleanup actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1704 should emphasize organophosphate toxicity, skin absorption, cholinesterase inhibitor recognition, decontamination, medical coordination and contaminated runoff control. Use ERG 153, SDS and local SOP.
Regulatory context: Tetraethyl dithiopyrophosphate is regulated as a toxic organophosphate hazardous material. Transportation, occupational exposure, spill reporting, pesticide/waste handling and environmental requirements may vary by jurisdiction. Verify current requirements through shipping papers, SDS, facility documents and applicable DOT, OSHA, EPA, NFPA, state or local authority guidance.
Storage & handling: Tetraethyl dithiopyrophosphate should be stored in tightly closed compatible containers in a secure, cool, well-ventilated toxic-material area away from heat, food/feed, oxidizers and unauthorized access. Storage should include spill containment, decontamination supplies and medical/emergency planning appropriate to the SDS.
UN 1704 Quick Details
Common Hazards of UN 1704
- HIGHLY TOXIC organophosphate liquid; inhalation, ingestion or skin absorption may be fatal.
- Can inhibit cholinesterase; exposure may require specialized medical evaluation.
- Low volatility does not eliminate skin absorption or contaminated clothing risk.
- Fire may produce phosphorus oxides, sulfur oxides and other toxic gases.
- Runoff and contaminated equipment may carry toxic pesticide residue.
- Containers may rupture or fail when heated.
- Avoid all skin contact and prevent spread of contaminated liquid.
Chemical Identity & Physical Properties
Pale yellow to colorless oily liquid with a garlic-like or sulfurous odor. Denser than water and poorly soluble in water.
| Also known as | SulfotepTEDPDithiopyrophosphoric acid tetraethyl esterEthyl thiopyrophosphateDithioneBladafum |
| CAS Number | 3689-24-5 |
| Appearance | Pale yellow to colorless oily liquid with a garlic-like or sulfurous odor. Denser than water and poorly soluble in water. |
| Flash Point | Not available, but likely >93°C (>200°F) due to high boiling point |
| Boiling Point | 136-139°C (277-282°F) at 2 mmHg; decomposes above 150°C (302°F) |
| Vapor Density | Approximately 9.7 (much heavier than air) |
| Water Reactivity | Hydrolyzes slowly in water; no violent reaction but degrades over time producing toxic breakdown products |
Fireground Response Guidance — UN 1704
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA and chemical protective clothing selected by hazmat specialists. Level A may be needed for close entry or unknown concentrations; avoid skin absorption and coordinate decontamination and medical evaluation.
Isolation & Evacuation
First Actions for a UN 1704 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, mist, aerosol or smoke 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 liquid, 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 vapor, dust, aerosol, fire involvement or unknown concentration is present.
- Use ERG Guide 153, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1704 — Tetraethyl dithiopyrophosphateUse 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.