Hydroquinone (CAS 123-31-9): storage and disposal
Hydroquinone is a crystalline solid with a long history on school and college shelves as old photographic developer stock, and in university stores and pharmacies as a raw material for skin preparations. It may cause an allergic skin reaction and serious eye damage, is suspected of causing genetic defects and cancer, and is very toxic to aquatic life. Its long term concerns are why old jars deserve attention.
- CAS number
- 123-31-9
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code, laboratory stock
- 16 05 06*
Corrosive
Harmful or irritant
Serious health hazard
Hazardous to the environment
What to do this week
- Without moving anything that looks damaged, 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 anything listed under "Do not store with" on this page. If nothing is listed, that does not prove it is safe with everything.
- If you no longer need it, add it to your disposal list so it can be included in a collection.
Safe storage in a school or lab
Suspected of causing cancer and genetic defects, a sensitiser and damaging to eyes: those hazards put it in a locked cabinet with a stock record, away from food and drink areas, acids and oxidisers. Photographic stock inherited by a school may sit in a darkroom cupboard among other chemicals, and it should be held in controlled storage instead. Keep the lid tight, stand the jar on a tray and keep goggles beside the cabinet. Pharmacy stock of the raw solid belongs apart from dispensing shelves and from finished creams, so that the two are never confused.
How to tell it has deteriorated
Fresh hydroquinone is white, and the first change with age is colour. Air slowly browns it, so a tan or brown surface and grey brown flecks mean the jar has had air or light, and the longer or more often it has been open, the darker it gets. Caking, a damp feel and dark staining at the neck and cap follow in a poorly sealed jar. Faded labels, a cap that will not turn and powder on the shelf are other signs. Browned crystals are still collected as they are. Record the colour at booking and never open the jar to look inside.
How it is disposed of
We arrange this by specialist collection. We do not publish a drain or general waste route for any chemical. It is normally packed in a toxic laboratory pack with compatible chemicals.
Leaving the site means specialist collection, with the jar packed in a lab pack alongside compatible organic solids. Waste code 16 05 06* usually applies in a lab pack, 16 05 08* to a discarded organic chemical outside one, and 18 01 06* to a pharmacy in a human healthcare setting. The producer confirms the classification. Because it is suspected of causing cancer and genetic defects and is very toxic to aquatic life, it must not be washed away, binned or burnt by site staff, and nobody should try to clean up or recover the crystals.
| Usual EWC code, laboratory stock | 16 05 06* |
|---|---|
| Discarded organic chemical, not a laboratory pack | 16 05 08* |
| Human healthcare setting | 18 01 06* |
| Usually classed as hazardous waste | Yes |
The code depends on where the waste came from and what it contains, and classifying it is the producer's duty. Use the waste code finder to see why.
Do not store with
- 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.
- 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.
- Sulfuric acidToxic stock is stored apart from acids. Several toxic salts release toxic gas in contact with acid.
Common quantities
Usually held as: solid.
Tell us the container size and how many you hold. An estimate is enough to start with, and some items cannot be priced until someone has looked at them.
Where it is commonly held
Hazard statements
- H302 Harmful if swallowed.
- H317 May cause an allergic skin reaction.
- H318 Causes serious eye damage.
- H341 Suspected of causing genetic defects.
- H351 Suspected of causing cancer.
- H400 Very toxic to aquatic life.
Precautionary statements
- P203 Obtain, read and follow all safety instructions before use.
- 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.
- P272 Contaminated work clothing should not be allowed out of the workplace.
- P273 Avoid release to the environment.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P301+P317 IF SWALLOWED: Get medical help.
- P302+P352 IF ON SKIN: Wash with plenty of water.
- P305+P354+P338 IF IN EYES: Immediately rinse with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
- P317 Get medical help.
- P318 If exposed or concerned, get medical advice.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- P333+P317 If skin irritation or rash occurs: Get medical help.
- P362+P364 Take off contaminated clothing. And wash it before reuse.
- P391 Collect spillage.
- 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 school inherited darkroom chemicals and the hydroquinone jar is brown. Is that a problem?
The colour is the usual effect of air and does not stop collection. Keep the jar closed in a locked cabinet, record the colour and amount, and book specialist collection instead of keeping it as spare stock.
Why is it locked away when it is classed as harmful, not toxic, if swallowed?
Because the long term classifications are the greater concern: suspected of causing genetic defects and cancer, plus sensitisation and serious eye damage. A locked cabinet with a record reflects those as well as the swallowing risk.
Is browned hydroquinone less hazardous than white?
Do not assume so. It carries the same classifications, and a darkened jar usually signals a poor seal. Treat colour as a reason to book collection sooner, not as a reason to relax.
