UN 1894 — Phenylmercuric hydroxide
Placard: Toxic. ERG Guide 151. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
UN 1894 is Phenylmercuric hydroxide, a toxic mercury compound assigned to ERG Guide 151. Dust, solution and runoff contamination are the major responder concerns.
Hazard overview: UN 1894 presents toxic mercury dust, ingestion, skin contact and contaminated-runoff hazards. Heating or fire may release mercury-containing fumes.
Response guidance: For a UN 1894 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 incompatible contact, control runoff and choose entry or fire-control actions based on monitoring, SDS and local SOP.
Firefighter training notes: Training for UN 1894 should emphasize persistent toxic contamination, dust or liquid control, skin absorption, runoff containment, decontamination waste and exposure documentation. Use ERG 151, SDS and local SOP.
Regulatory context: Phenylmercuric hydroxide 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: Phenylmercuric hydroxide should be stored in tightly closed compatible containers in a secure toxic-material area with secondary containment, dust control, restricted access and waste/decontamination planning according to SDS.
UN 1894 Quick Details
Common Hazards of UN 1894
- HIGHLY TOXIC mercury compound; may be harmful or fatal if inhaled, ingested or absorbed through skin.
- Dust or solution can contaminate clothing, tools, equipment and runoff.
- Fire or heating may produce toxic mercury fumes and irritating decomposition products.
- Runoff may pollute waterways and create persistent mercury contamination.
- Containers may rupture or fail when heated.
- Specific solubility and reactivity should be confirmed from SDS.
- Avoid skin contact and prevent dust from becoming airborne.
Chemical Identity & Physical Properties
White to cream-colored crystalline powder or solid. Odorless or slight aromatic odor. Solid at room temperature.
| Also known as | Phenylmercury hydroxideHydroxyphenylmercuryPMHPhenylhydroxymercuryPhenylmercuric acid |
| CAS Number | 100-57-2 |
| Appearance | White to cream-colored crystalline powder or solid. Odorless or slight aromatic odor. Solid at room temperature. |
| Flash Point | Not applicable (non-flammable solid) |
| Boiling Point | Decomposes before boiling |
| Vapor Density | Not applicable (solid) |
| Water Reactivity | Slightly soluble in water; no significant reaction |
Fireground Response Guidance — UN 1894
Extinguishing Media
PPE Requirements
Use positive-pressure SCBA for dust, vapor, fire or confined-space exposure. Chemical-resistant gloves, eye/face protection and protective clothing should be selected from SDS; prevent skin contact and contaminated dust spread.
Isolation & Evacuation
First Actions for a UN 1894 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 or spray and avoid skin or eye contact.
- Do not touch or walk through spilled material unless properly trained and wearing appropriate protective equipment.
- Prevent contaminated dust, liquid, runoff and decontamination waste from spreading.
- 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, fire involvement, water reaction or unknown concentration is present.
- Use ERG Guide 151, shipping papers, SDS, air monitoring and incident command for protective actions.
📋 Copy & Share Field Card
UN 1894 — Phenylmercuric hydroxideUse 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.