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Chemical collection and stock control for UK schools, universities and hospitals

White phosphorus (CAS 12185-10-3): storage and disposal

Some school, college and university stores still hold white phosphorus as sticks under water, sealed in a container inside secondary containment. It catches fire on its own if exposed to air, is fatal if swallowed or inhaled, and causes severe burns. The water level decides nearly everything about how it is handled. Holdings are not quoted online and go through a manual enquiry, while exposed smoking material is an emergency.

CAS number
12185-10-3
Form
Solid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable
  • Corrosive pictogramCorrosive
  • Acute toxicity pictogramAcute toxicity
  • Hazardous to the environment pictogramHazardous to the environment

This chemical is a manual enquiry

This can become unstable or explosive, especially if it is old or has dried out. Nobody should move it until someone competent has looked at it, so we start with a conversation and usually a store assessment.

Ignites in air if its water cover is lost.

It cannot be priced through a form. Please do not open or move it. Call us or send an enquiry and we will talk through the safe next step, which is often a store assessment.

What to do this week

  1. Leave it where it is. If it looks old, crystalline or damaged, do not open or move it and keep people away from the shelf.
  2. Write down the label wording, the rough age and where it is stored, from a safe distance.
  3. Send us those details, and a photo if you can take one without touching it.

Safe storage in a school or lab

Oxidisers head the list: potassium chlorate, potassium permanganate, hydrogen peroxide, chromium trioxide and calcium hypochlorite can all ignite or explode with it, so it has no place near the oxidiser shelf. Air is the other concern, and only the water keeps it out. The arrangement to look for is a sealed container of sticks under water, inside secondary containment, in a fire-resistant cabinet, where a knock will not reach it. A store that freezes in winter can crack the glass, and that is easily overlooked in an unheated outbuilding. Read the water level from outside at each stock check and write it down, as a slow fall shows up that way. Do not open the container or top up the water yourself.

How to tell it has deteriorated

Yellow waxy sticks under clear water are normal, and a dull or whitish surface tells you little. Light can give the sticks a reddish tint over time, which does nothing to make them less hazardous. The level is what matters. Water falling towards the top of the sticks means a seal is failing or it has been evaporating, and if it is lost the phosphorus can ignite. Look for a tide mark on the glass, a cracked container, or water standing in the secondary containment. Exposed smoking material is an emergency: leave the room, keep others out and call the emergency services. Short of that, do not open or move anything, and get a specialist assessment quickly.

How it must be disposed of

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Do not open the container, take out a stick, try to burn or bury it, or tip it into a sink, a drain, a bin or a skip. This site does not quote for it online, and the online quote path does not accept it. Send a manual enquiry, and a store assessment is recommended. A competent chemist has to see it in person, and a warning sign may bring in an explosives or emergency specialist. Say how many sticks or containers you hold, where the water stands relative to the sticks and what the secondary containment looks like. Do not move it or try to make it safe in the meantime. School and university stock normally takes code 16 05 06*.

Waste codes and transport details for White phosphorus
EWC code, laboratory chemicals16 05 06*
Discarded inorganic chemical, not a laboratory pack16 05 07*
Hazardous wasteYes

The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.

Do not store with

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

Show 7 more
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganatePhosphorus can ignite or explode with oxidisers.
  • Sodium chloratePhosphorus can ignite or explode with oxidisers.
  • Sodium dichromatePhosphorus can ignite or explode with oxidisers.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.
  • Zinc chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

Common quantities we collect

Usually held as: sticks under water.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Hazard statements

  • H250 Catches fire spontaneously if exposed to air.
  • H300 Fatal if swallowed.
  • H314 Causes severe skin burns and eye damage.
  • H330 Fatal if inhaled.
  • H400 Very toxic to aquatic life.

Substance as classified, dilutions may differ.

Questions

The water in our phosphorus jar has dropped, but the sticks are still covered. Can we top it up?

No. Topping up means opening the container, and that risks exposing phosphorus to air. Leave it closed and in place. Treat the drop as urgent and send an enquiry with the level and the state of the outer containment, so a specialist can assess it.

Our store also lists red phosphorus. Is that the same thing?

They are forms of the same element, but they look different and are held differently. This page covers waxy yellow or white sticks under water. If a label is unclear, or a container holds water, treat it as white phosphorus and leave it closed until someone competent has seen it.

A stick is exposed and smoking. What do we do?

Treat it as an emergency. Leave the room, close the door if that is possible without going near it, keep everyone out and call the emergency services, telling them it is white phosphorus. Do not touch it or try to cover it yourself.

Should we move the jar to a safer cabinet before anyone assesses it?

Leave it where it is, even if the current cabinet is not ideal. A dropped or knocked container is a far greater danger than a poor shelf position. Note the cabinet and anything stored nearby, especially oxidisers, and include that in your enquiry.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: GB mandatory classification list (HSE), retrieved 31 Oct 2026. Formula P. EC number 231-768-7.

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