UN 2501 — Tris-(1-aziridinyl)phosphine oxide, solution
Placard: Toxic. ERG Guide 152. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 2501 At a Glance
UN 2501 (Tris-(1-aziridinyl)phosphine oxide, solution) is listed as DOT Class 6 Toxic and is assigned to ERG Guide 152. Use this page to review placard data, common hazards, PPE notes, isolation context, first actions, and related UN numbers.
UN 2501 is Tris-(1-aziridinyl)phosphine oxide, solution, a highly toxic solution assigned to ERG Guide 152. Exact concentration/solvent must be verified from SDS.
Hazard overview: HIGHLY TOXIC aziridine/phosphoramide solution; inhalation, ingestion or skin absorption may be fatal. Skin contact and contaminated clothing can extend exposure. Combustible material: may burn but does not ignite readily.
Response guidance: For UN 2501, isolate the area, avoid skin contact and use SCBA where vapor, dust, mist or fire is present. Contain toxic/corrosive runoff and verify product controls with SDS and ERG 152.
Firefighter training notes: Training for UN 2501 should emphasize toxic/corrosive exposure routes, skin absorption, SCBA use, decontamination, runoff containment and SDS verification. Use ERG 152, SDS and local SOP.
Regulatory context: Tris-(1-aziridinyl)phosphine oxide, solution is regulated as a hazardous material for transport and emergency response. Storage, exposure, spill reporting, waste and fire-code duties depend on quantity, concentration and jurisdiction; verify shipping papers, SDS and local authority requirements.
Storage & handling: Tris-(1-aziridinyl)phosphine oxide, solution should be stored in tightly closed compatible containers with ventilation, secondary containment, restricted access and SDS-based segregation from incompatible materials.
UN 2501 Quick Details
Common Hazards of UN 2501
- HIGHLY TOXIC aziridine/phosphoramide solution; inhalation, ingestion or skin absorption may be fatal.
- Skin contact and contaminated clothing can extend exposure.
- Combustible material: may burn but does not ignite readily.
- May be reactive or unstable under heat or contamination depending on solution composition.
- Fire may produce nitrogen oxides, phosphorus oxides and other toxic gases.
- Runoff may carry toxic solution contamination.
- Exact solvent/concentration must be verified from SDS and shipping papers.
Chemical Identity & Physical Properties
Colorless to pale yellow liquid solution. Odorless or slight amine-like odor. Highly toxic organic compound used historically as a chemotherapy agent and insect chemosterilant.
| Also known as | TEPATris(1-aziridinyl)phosphine oxideTriethylenephosphoramideAPOTris(ethylenimino)phosphine oxide |
| CAS Number | 545-55-1 |
| Appearance | Colorless to pale yellow liquid solution. Odorless or slight amine-like odor. Highly toxic organic compound used historically as a chemotherapy agent and insect chemosterilant. |
| Flash Point | Not available for solution; base compound is combustible |
| Boiling Point | Decomposes before boiling at approximately 80-100°C (176-212°F) |
| Vapor Density | Heavier than air (MW ~173) |
| Water Reactivity | Soluble in water; no violent reaction but releases toxic vapors |
Fireground Response Guidance — UN 2501
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for vapor, dust, mist, fire or confined-space exposure. Wear chemical-resistant gloves, boots, eye/face protection and protective clothing.
Isolation & Evacuation
First Actions for a UN 2501 Incident
- Call 911 and the emergency response number on the shipping paper, if available.
- Keep unauthorized personnel away and establish incident command.
- Stay upwind, uphill and upstream.
- Avoid breathing vapor, dust, mist, smoke or fumes and avoid skin or eye contact.
- Do not touch damaged containers or spilled material without proper training and PPE.
- Prevent contaminated dust, liquid, runoff and decontamination waste from spreading.
- Ventilate confined spaces only after monitoring and only if properly trained and equipped.
- Use ERG Guide 152, SDS, shipping papers and monitoring to set isolation, evacuation and entry decisions.
📋 Copy & Share Field Card
UN 2501 — Tris-(1-aziridinyl)phosphine oxide, soluUse 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.