Selenium (CAS 7782-49-2): storage and disposal
Selenium powder is kept in college and university stores, usually in a small jar with a long stock history. It is classified as toxic if swallowed or inhaled, a cause of organ damage after prolonged or repeated exposure and a long lasting hazard to aquatic life. That makes locked storage and a current stock record the first requirements.
- CAS number
- 7782-49-2
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
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 in a school or lab
College stores typically hold selenium as one small jar among the inorganic reagents, and it is easy for it to drift onto an open shelf. It is toxic if swallowed or inhaled, so it belongs in a locked cabinet with a stock record, away from food and drink areas, acids and oxidising stock. Several toxic salts release toxic gas with acid, and a reaction with oxidisers could release toxic vapours. Keep the lid tight, because powder that escapes spreads, and check the stock record against the jar at each audit. Selenium powder can be grey or red depending on its form, so the label should name the form.
How to tell it has deteriorated
The powder may be grey or red depending on its form, and either can look unchanged for years. The substance gives few visible signs of age, so the container tells you more: a lid that no longer closes, powder round the neck or on the shelf, a cracked jar, a faded label or no date of receipt. A change of colour inside a single jar, a layer of different powder or a damp patch should be recorded as possible contamination. If the label is unreadable, leave the jar closed and ask for an assessment instead of trying to identify the contents.
How it must be disposed of
By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a toxic laboratory pack with compatible chemicals.
Nobody should try to wash selenium powder away, burn it or react it into something else, and it must not go into a sink, a drain, a general bin or a skip. It is entered as 16 05 06*, and the only route is specialist collection. Record that it is powder, how much is left, whether the jar is sealed and whether the label can be read. A jar with no label is described as such and not as selenium, so the collector can assess it before packing.
| EWC code, laboratory chemicals | 16 05 06* |
|---|---|
| Discarded inorganic chemical, not a laboratory pack | 16 05 07* |
| 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 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 we collect
Usually held as: powder.
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
- H301 Toxic if swallowed.
- H331 Toxic if inhaled.
- H373 May cause damage to organs through prolonged or repeated exposure.
- H413 May cause long lasting harmful effects to aquatic life.
Precautionary statements
- 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.
- P270 Do not eat, drink or smoke when using this product.
- P271 Use only outdoors or in a well-ventilated area.
- P273 Avoid release to the environment.
- P301+P316 IF SWALLOWED: Get emergency medical help immediately.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P316 Get emergency medical help immediately.
- P319 Get medical help if you feel unwell.
- P321 Specific treatment (see supplemental first aid instruction on this label).
- P330 Rinse mouth.
- 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
How should selenium be stored in a college store?
In a locked cabinet with a stock record, away from food and drink areas, acids and oxidising stock. It is classified as toxic if swallowed or inhaled, so the cabinet and record are essential, and the lid needs to be tight so powder cannot escape.
Does selenium powder go off?
No fixed life is set for it, and it gives few visible signs of age. The jar and its records matter more than the powder. A sealed, labelled, dated jar can be described confidently for collection, while an unlabelled one should be left closed and reported.
The colour in our selenium jar differs from the one next to it. Is something wrong?
Not necessarily. Selenium powder can be grey or red depending on its form. A colour that differs within one jar, or a damp or caked layer, is different and should be recorded as possible contamination before collection.
