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

Ethylene oxide (CAS 75-21-8): storage and disposal

Ethylene oxide is a sterilising gas, held in small cartridges beside bench sterilisers in clinics, pharmacies and university departments. It is extremely flammable, toxic if inhaled or swallowed, causes severe burns and may cause cancer and genetic defects. It may damage fertility and is suspected of damaging the unborn child. Those classifications, and the fact that cartridges need specialist handling, decide everything about how an unwanted one is dealt with.

CAS number
75-21-8
Form
Gas
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 04*
  • Flammable pictogramFlammable
  • Gas under pressure pictogramGas under pressure
  • Corrosive pictogramCorrosive
  • Acute toxicity pictogramAcute toxicity
  • Serious health hazard pictogramSerious health hazard

This chemical is a manual enquiry

This is held as a compressed gas. Cylinders are usually returned to the supplier or handled separately, and they do not go into a laboratory pack.

Held as a compressed or liquefied gas in a pressure container.

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

Nothing that can feed a fire or attack a seal belongs near ethylene oxide cartridges. Oxidisers can ignite the gas or make a fire far more intense, while fumes from acids and corrosive stock break down containers. The common mistake is the handy cupboard beside the steriliser, shared with alcohol hand rub and surface disinfectant, so check what is really on that shelf. Keep sealed cartridges in their original carton, locked in a ventilated place and well away from heat, because they hold gas under pressure that may explode if heated. Log each one on a stock record, including any that were pierced but never finished. Do not puncture or vent a cartridge, however little seems to be left.

How to tell it has deteriorated

An intact cartridge in its original dated carton looks unremarkable, and the gas gives few visible signs of age while sealed. What does not look right is a crushed or dented casing, rust on the metal, a split carton or a cartridge sitting loose with no record of whether it was used. Smell is a poor test here. The faint sweet odour only becomes noticeable at levels well above what matters for exposure, so the absence of a smell proves nothing. If a smell is present, or a casing is visibly damaged, leave the room, keep others out and call the person responsible for the steriliser. Do not handle a damaged cartridge, as the contents cause severe skin burns and eye damage.

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.

Leaving the site takes a specialist arrangement, because these cartridges need specialist handling and pressure containers are barred from a lab pack. Start with a manual enquiry giving the number of cartridges, whether any have been pierced, the steriliser they fit and the room they are in. We do not quote for them online, and a store assessment is recommended. The steriliser's maker may also be able to say whether its cartridges are taken back. Never run an empty cycle to use one up, and never vent, puncture or put a cartridge out with clinical or general waste. Until advice arrives they stay where they are, cool and locked away.

Waste codes and transport details for Ethylene oxide
EWC code, laboratory chemicals16 05 04*
Hazardous wasteYes

Gases in pressure containers are assessed by manual enquiry, usually with return to the cylinder owner.

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

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Calcium hypochloriteOxidisers can ignite flammable materials or make a fire far more intense.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideOxidisers can ignite flammable materials or make a fire far more intense.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganateOxidisers can ignite flammable materials or make a fire far more intense.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
Show 2 more
  • 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: sterilising cartridges.

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

  • H220 Extremely flammable gas.
  • H280 Contains gas under pressure; may explode if heated.
  • H301 Toxic if swallowed.
  • H314 Causes severe skin burns and eye damage.
  • H331 Toxic if inhaled.
  • H335 May cause respiratory irritation.
  • H336 May cause drowsiness or dizziness.
  • H340 May cause genetic defects.
  • H350 May cause cancer.
  • H360Fd May damage fertility. Suspected of damaging the unborn child.
  • H372 Causes damage to organs through prolonged or repeated exposure.
Precautionary statements
  • P203 Obtain, read and follow all safety instructions before use.
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P222 Do not allow contact with air.
  • P260 Do not breathe dust, fume, gas, mist, vapours or spray.
  • P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P264+P265 Wash hands and exposed skin thoroughly after handling. Do not touch eyes.
  • P270 Do not eat, drink or smoke when using this product.
  • P271 Use only outdoors or in a well-ventilated area.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P301+P316 IF SWALLOWED: Get emergency medical help immediately.
  • P301+P330+P331 IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.
  • P302+P361+P354 IF ON SKIN: Take off immediately all contaminated clothing. Immediately rinse with water for several minutes.
  • P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
  • P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P316 Get emergency medical help immediately.
  • P317 Get medical help.
  • P318 If exposed or concerned, get medical advice.
  • P319 Get medical help if you feel unwell.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P330 Rinse mouth.
  • P363 Wash contaminated clothing before reuse.
  • P377 Leaking gas fire: Do not extinguish, unless leak can be stopped safely.
  • P381 In case of leakage, eliminate all ignition sources.
  • P403 Store in a well-ventilated place.
  • P403+P233 Store in a well-ventilated place. Keep container tightly closed.
  • P405 Store locked up.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.
  • P301+P317 IF SWALLOWED: Get medical help.
  • P302+P352 IF ON SKIN: Wash with plenty of water.
  • P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P332+P317 If skin irritation occurs: Get medical help.
  • P337 If eye irritation persists:
  • P337+P317 If eye irritation persists: Get medical help.
  • P362+P364 Take off contaminated clothing. And wash it before reuse.
  • P410+P403 Protect from sunlight. Store in a well-ventilated place.

Substance as classified, dilutions may differ.

Questions

Can we run a spare ethylene oxide cartridge through the steriliser just to use it up?

No. A cycle with no real load still releases a gas that is toxic if inhaled and may cause cancer, and the used cartridge still needs dealing with. Leave an unused, intact cartridge sealed in its original carton and raise a manual enquiry. If a cartridge has already been pierced or used, do not handle or repackage it. Describe its condition in the enquiry so that the specialist can determine the appropriate collection arrangements.

A retired steriliser still has a cartridge inside it. Should we take it out before it goes?

Leave it alone. Nobody can tell from outside whether that cartridge is spent or was pierced part way through a cycle. Keep the steriliser where it is, label it clearly so that nobody sends it for scrap, and ask for advice before any part of it is moved.

Our cartridges are past the date on the carton. Are they weaker or less of a risk now?

Do not assume so. A date on the carton concerns how well a cycle will work, and says nothing about the gas becoming less flammable or less harmful. Regard every sealed cartridge as full and under pressure, however old the carton looks, and add it to your stock record.

Which people should be kept away from the ethylene oxide store?

Limit access to staff who need it, and tell anyone pregnant or planning a family that it is there, because it may damage fertility and is suspected of damaging the unborn child. Occupational health should be part of that conversation. Locked storage also stops cleaners coming across it by accident.

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

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula C2H4O. EC number 200-849-9.

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