UN 1651 — Naphthylthiourea
Placard: Toxic. ERG Guide 153. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1651 is Naphthylthiourea, a toxic organic solid assigned to ERG Guide 153. Responders should avoid dust exposure, skin contact and contaminated runoff.
Hazard overview: UN 1651 presents toxic dust, ingestion and skin-contact hazards. Fire may produce irritating or toxic gases, and dry powder can contaminate clothing, tools and surfaces.
Response guidance: For a UN 1651 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 or vapor exposure, control runoff and choose entry or cleanup actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1651 should emphasize toxic dust exposure, combustible organic solid behavior, PPE selection, decontamination and runoff control. Use ERG 153, SDS and local SOP.
Regulatory context: Naphthylthiourea is regulated as a hazardous material for transportation and emergency response purposes. Transportation, workplace exposure, spill reporting, waste handling, storage and environmental requirements may vary by formulation, 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: Naphthylthiourea should be stored in tightly closed compatible containers in a secure toxic-material area according to SDS and local hazardous materials procedures.
UN 1651 Quick Details
Common Hazards of UN 1651
- TOXIC organic solid; inhalation, ingestion or skin contact may cause serious injury.
- Dust can create inhalation and surface contamination hazards.
- Combustible material: may burn but does not ignite readily.
- Fire may produce irritating, corrosive and/or toxic gases.
- Runoff may carry toxic contamination to drains or waterways.
- Containers may rupture or fail when heated.
- Specific toxicity depends on formulation and should be verified from SDS.
Chemical Identity & Physical Properties
White to gray odorless crystalline powder or solid at room temperature. May have a slight bitter taste.
| Also known as | ANTUAlpha-naphthylthiourea1-NaphthylthioureaRattrackBantu |
| CAS Number | 86-88-4 |
| Appearance | White to gray odorless crystalline powder or solid at room temperature. May have a slight bitter taste. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Not applicable (decomposes before boiling) |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | No significant reaction with water |
Fireground Response Guidance — UN 1651
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS; avoid dust and contaminated skin contact.
Isolation & Evacuation
First Actions for a UN 1651 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 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 dust, vapor, 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 1651 — NaphthylthioureaUse 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.