What counts as hazardous waste in a school or lab

The test the law applies to lab waste

You must classify your waste before it is collected, disposed of or recovered. Nobody else carries that first step for you, although a contractor can advise. The classification decides how the waste is handled, who can take it and what goes on the paperwork.

Classification rests on a six digit code from the List of Wastes, often called the EWC code. An asterisk marks a hazardous entry. Some entries are hazardous whatever the contents. Amalgam waste from dental care, 18 01 10*, is one of them. Others come in pairs, known as mirror entries, where the answer depends on what the waste contains.

That second group matters to labs, because the main chemical codes work this way. 16 05 06* covers laboratory chemicals consisting of or containing hazardous substances. 18 01 06* and 18 01 07 are the hazardous and non-hazardous pair for chemicals from human healthcare.

School and laboratory waste, sorted by example

The table shows how familiar items tend to fall. It is a starting point for your own assessment and does not replace it.

The last row is the one to treat with caution. A clean, labelled bottle of a harmless salt may well be non-hazardous. A bottle whose contents you cannot vouch for cannot be treated that way.

Five steps to decide if your waste is hazardous

1. Name it. Write down the chemical, the form and the approximate quantity. If the label is gone, stop here and treat the container as unknown.

2. Work out where it came from. WM3 sends you to the chapter for the source of the waste first. A hospital laboratory looks at chapter 18. Chapter 16, which holds the general laboratory chemical entries, comes after the source chapters and the chapters for solvents and packaging.

3. Check the hazard data. The supplier's safety data sheet gives you the classification of the product as supplied. Old stock may no longer match it, so note the age and condition.

4. Choose the code. Pick the entry that fits best, and note the hazardous properties it has. On a consignment note you must not leave out a property the waste has, and you must not add one it does not.

5. Keep it apart. It is illegal to mix hazardous waste with non-hazardous waste or with another hazardous waste. In a lab, this is what stops the half-full bottles being tipped into one convenient container. HTM 07-01 also says waste chemicals should stay out of clinical, offensive and municipal bins, and that this mixing is prohibited in England and Wales.

Unknown contents count as hazardous

WM3 is firm on this. Where the composition of a mirror entry waste is not known and genuinely cannot be determined, it must be classified under the hazardous entry. Direct testing cannot be used to show that a waste of unknown composition is non-hazardous.

Our view is that the rule suits a chemical store well. A bottle with half a label has no route to "probably fine". It goes forward as hazardous, and anything that looks unstable goes to a specialist before anyone handles it. Crystals around a cap, a swollen container or a very old ether tin all fall into that group. Leave them where they are, keep people away and get a specialist assessment. If there is immediate danger, call the emergency services.

What your duties are once it is classified

In England, a producer of hazardous waste must store it safely and apart from other waste, use authorised businesses to collect it, and complete a consignment note for every movement. You keep one copy of the note and give two copies to the carrier. Records are held for three years at the premises that produced the waste.

The rest of the UK differs in its detail. Scotland uses the term special waste and a consignment note bearing a SEPA code. Northern Ireland has its own regulations and a coded consignment note issued through the Northern Ireland Environment Agency. Wales requires premises registration above 500kg of hazardous waste a year.

Where school and hospital labs usually go wrong

Three mistakes come up again and again. The first is using the product's data sheet as the final answer. A data sheet describes what the supplier sold, and your waste may be decades older or mixed with something else. The second is describing a mixed consignment by its short code alone. The consignment note guidance says the short List of Wastes description is not normally enough, so a note reading "laboratory chemicals" falls short when the drum holds named solvents.

The third belongs to hospitals. Preserved tissue sits across two streams, because chemically preserved anatomical waste takes the chemical code together with the anatomical one. It is an easy one to book under a single code, and the healthcare classification guidance is the place to check it during a histology lab's waste audit.

Our work on laboratory chemical disposal starts from this classification, with collection arranged through registered waste carriers.