Cadmium (CAS 7440-43-9): storage and disposal
Legacy cadmium usually appears as rods or small pieces of soft, bluish white metal in the back of a school, college or university store. It looks inert, which is the problem. As classified it may cause cancer and is fatal if inhaled, and long exposure damages the kidneys. Fine dust and fumes are the main risk, so what decides its handling is keeping the metal whole and undisturbed until it is collected.
- CAS number
- 7440-43-9
- Form
- Solid
- Storage class
- Toxic
- Signal word
- Danger
- Usual EWC code
- 16 05 06*
Acute toxicity
Serious health hazard
Hazardous to the environment
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
Rods and offcuts are the usual form, often in an old jar or a small box of mixed metal samples with a handwritten label. Pull cadmium out of any such set on paper, in the stock record, and give it a place of its own in the locked toxic cabinet, with acids and oxidisers kept elsewhere. A loose rod on a metals shelf is the common mistake, because it invites someone to file, saw or heat it for a demonstration, and dust or fume is how it does its harm. Nobody should do any of those things with old stock. Keep the jar closed so that any powder or filings inside stay there. Label it plainly, as an unmarked grey rod is easily misidentified.
How to tell it has deteriorated
Sound metal is soft and silvery with a bluish tint, usually dulled by a thin grey tarnish that is normal and does not spread. It gives few visual signs beyond that, and age changes it very little. What needs attention is what has happened around it. Filings, powder or a saw cut suggest someone has worked on the rod, and any loose dust in the jar is the form that matters most. A faded or missing label is the other usual finding, along with a lost stock record. If powder is present, keep the jar closed and do not tip it out to see how much there is. A rod that nobody can identify should be described as an unknown metal.
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.
Grouped with other toxic metals, it goes into a lab pack as a solid and keeps well away from any acids and oxidisers in the same collection. That needs an accurate description, so say whether you hold rods, offcuts or powder, and give a rough count or weight. The mistake to avoid is treating it as scrap: it must not go into a metal recycling bin, a general waste bin, a skip, a sink or a drain, and nobody should cut it to fit a container or try to treat it first. Specialist collection is the only route, and its long lasting harm to aquatic life is one more reason for that. School and university stock normally takes code 16 05 06*.
| 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: legacy stock, rods.
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
- H330 Fatal if inhaled.
- H341 Suspected of causing genetic defects.
- H350 May cause cancer.
- H361fd Suspected of damaging fertility. Suspected of damaging the unborn child.
- H372 Causes damage to organs through prolonged or repeated exposure.
- H410 Very toxic to aquatic life with long lasting effects.
Precautionary statements
- P203 Obtain, read and follow all safety instructions before use.
- P260 Do not breathe 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.
- P280 Wear protective gloves, protective clothing, eye protection and face protection.
- P284 In case of inadequate ventilation wear respiratory protection.
- P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.
- P316 Get emergency medical help immediately.
- P318 If exposed or concerned, get medical advice.
- P319 Get medical help if you feel unwell.
- P320 Specific treatment is urgent (see supplemental first aid instruction on this label).
- P391 Collect spillage.
- 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
Can old cadmium rods go in with our scrap metal?
No. Cadmium may cause cancer and damages the kidneys with long exposure, so it remains a hazardous chemical waste even in solid form. Keep rods apart from any scrap collection and list them separately when you arrange a specialist collection, giving the form and approximate quantity.
Should we keep the rods for occasional demonstrations?
Only if there is a planned use with its own risk assessment, and even then filing, cutting or heating it is the problem, because dust and fumes are the main risk. Stock kept merely in case it is needed is better listed for collection.
How do we tell if a grey rod in an old set is cadmium?
Without a label, you generally cannot tell by looking, and nobody should cut, file or test it to find out. Record it as an unidentified metal, with any set name, supplier marking or stock entry that survives, and pass that description on when arranging collection.