Phenol: safe storage and disposal
Phenol (CAS 108-95-2) is an old laboratory chemical with a modern use. School stores may still hold crystals from past practicals, while molecular biology labs use liquefied or Tris-saturated phenol for nucleic acid work. Its GHS signal word is Danger. The hazard statements are H301 Toxic if swallowed, H311 Toxic in contact with skin, H314 Causes severe skin burns and eye damage, H331 Toxic if inhaled, H341 Suspected of causing genetic defects and H373 May cause damage to organs through prolonged or repeated exposure.
Phenol's particular danger is skin contact. It passes through the skin readily and has a numbing effect, so a serious burn may hurt less than it should. That shapes how you plan for it.
- CAS number
- 108-95-2
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Corrosive
Acute toxicity
Serious health hazard
What to do this week
- Check the label is readable and write down the opened date if it is not already there.
- Check it is stored as toxic stock and apart from the items listed under "Do not store with".
- If you no longer need it, add it to your disposal list so it goes on the next collection.
Safe storage of phenol in a school or lab
Keep phenol with toxic stock, in a locked location with restricted access, in the original closed and labelled container. Keep it low on a shelf and inside a secondary tray, so a dropped or leaking bottle stays contained. Crystals melt at only slightly above room temperature, so avoid warm positions such as a shelf above a radiator.
Check that your emergency arrangements cover phenol in particular before anyone opens a container. Your supplier's safety data sheet sets out the first aid measures, and your risk assessment should say what must be within reach of the bench where it is used.
How to tell phenol has deteriorated
Fresh phenol crystals are colourless or white. With age, light and air, they turn pink and then red or brown. That colour marks oxidation, and it is a good sign that the bottle is old. Crystals may also have clumped or liquefied in the bottle, especially if they have taken up water from the air, and fumes may have attacked the cap.
Old screw caps may be fused or brittle. Do not force them. If a cap has failed, the outside of the bottle is contaminated or the label has gone, leave the bottle in place and arrange a specialist look at it. Tris-saturated phenol in a lab fridge can also separate or darken. Record the date you notice this, and treat the bottle as waste.
How phenol must be disposed of
Phenol goes by specialist collection. Do not put it down a sink, including small volumes from a lab protocol. It is toxic and corrosive, and must be kept out of drains and sent through a hazardous waste collection.
| Setting | Usual List of Wastes code | Hazardous |
|---|---|---|
| Laboratory chemical, including school and university | 16 05 06* | Yes |
| Discarded organic chemical, not in a laboratory pack | 16 05 08* | Yes |
| Human healthcare setting | 18 01 06* | Yes |
For transport, phenol is commonly UN 1671 as a solid, packing group II. Molten phenol and phenol solutions have other UN numbers, so check the product's data sheet.
Include gloves, tips and paper towels contaminated with phenol in your thinking. They should go in a labelled solid waste stream and not the general bin. Mixed lab clear-outs that include phenol come under laboratory chemical disposal, and a line on the list should describe its form and its age.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Hazardous waste | Yes |
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 phenol with
- Formalin, neutral buffered formalin and paraformaldehyde. Formaldehyde reacts with phenol, and a pathology or research lab may hold all of them close together.
- Oxidisers such as hydrogen peroxide, potassium permanganate, potassium nitrate and calcium hypochlorite. Toxic and oxidising stock are stored apart, because a reaction could release toxic vapour.
- Acids, including nitric acid and hydrochloric acid. Toxic stock is kept separate from acids.
- OxidiserToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- AcidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Named chemicals to keep apart
- Acetic acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Calcium hypochloriteToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- FormalinFormaldehyde reacts with these materials. With hydrochloric acid it can form a potent carcinogen.
- Hydrochloric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Hydrogen peroxideToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Nitric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
- Potassium nitrateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
- Potassium permanganateToxic and oxidising stock are stored apart. A reaction could release toxic vapours.
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- Sulfuric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Common quantities of phenol collected
Schools tend to have one small bottle of crystals, sometimes decades old. Research labs may hold several bottles of buffered or liquefied phenol, plus regular small volumes of phenol waste from extraction protocols. Pathology and histology departments may hold phenol as a component of older stains or reagents, so check the label for mixtures.
Usually held as: crystals, liquefied about 90%, Tris-saturated.
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.
Phenol in different sectors
Schools and colleges. Phenol is often a legacy item that no longer features in the scheme of work. Check with your advisory service, either CLEAPSS or SSERC, and if it has no teaching purpose, put it on your disposal list.
Universities and research. Phenol waste from nucleic acid extraction often contains chloroform. Keep it in a labelled chlorinated waste container of its own, kept closed in a ventilated location, and give it a proper description. Where it may contain biological material, say so.
Hospitals and pathology. Waste chemicals stay out of clinical and offensive waste, with 18 01 06* as the hazardous code for chemicals from human healthcare.
Dental practices. Some older materials and disinfectants contain phenol. Check the data sheet before assuming they are ordinary waste.
Hazard data from PubChem GHS classification, retrieved 31 October 2026. Guidance only. Check your own risk assessment and your supplier's safety data sheet.
Hazard statements
- H301 Toxic if swallowed.
- H311 Toxic in contact with skin.
- H314 Causes severe skin burns and eye damage.
- H331 Toxic if inhaled.
- H341 Suspected of causing genetic defects.
- H373 May cause damage to organs through prolonged or repeated exposure.
Precautionary statements
- P203 Obtain, read and follow all safety instructions before use.
- P260 Do not breathe dust, fume, gas, mist, vapours or spray.
- P261 Avoid breathing dust, fume, gas, mist, vapours or spray.
- P262 Do not get in eyes, on skin, or on clothing.
- P264 Wash hands and exposed skin thoroughly after handling.
- 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+P352 IF ON SKIN: Wash with plenty of water.
- 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.
- 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.
- P361+P364 Take off immediately all contaminated clothing. And wash it before reuse.
- P363 Wash contaminated clothing before reuse.
- 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.
Substance as classified, dilutions may differ.
Questions
Our phenol crystals have gone pink. Are they still collectable?
Yes. Pink or red crystals are the usual result of age and air, and they are collected as they are. Keep the cap closed, stand the bottle in a tray, and record the colour at booking.
Why must phenol be kept apart from formalin on a histology bench?
Formaldehyde reacts with phenol, and a spill or a shared tray could bring them together. Give phenol its own place in the locked cabinet, with formalin, neutral buffered formalin and paraformaldehyde held elsewhere.
Why is a phenol splash treated as an emergency when it does not hurt?
It is absorbed quickly through skin and burns can be painless at first, so the lack of pain proves nothing. Your site first aid procedure and emergency contacts should name phenol specifically.
What do we record for a buffer-saturated phenol bottle?
The label name as printed, the amount, and what the bottle shows, including any separate layer above the phenol. Say it is a saturated preparation rather than neat phenol so the packer describes it correctly.
