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Chemical collection and stock control for UK schools, universities and hospitals

Boron (CAS 7440-42-8): storage and disposal

Boron is held as a fine powder in college and university stores, typically as one of the less used elements on the shelf. It is not normally classified as hazardous, but it remains a chemical waste that needs an accurate description. Dust control, identification and separation from ignition sources and oxidising chemicals matter more than visible changes in the powder.

CAS number
7440-42-8
Form
Solid
Storage class
General
Usual EWC code, laboratory stock
16 05 09

What to do this week

  1. Without moving anything that looks damaged, check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as general 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.
  3. 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

In a college or university store boron powder usually sits in a small jar among the elements, and the most common fault is a lid that has not been fully closed. Keep boron powder dry and labelled in a tightly closed container, away from ignition sources and oxidising chemicals. Fine boron powder can be combustible, so its form and the supplier's classification decide where it belongs. Fine powder travels, so close the lid fully and keep the jar away from airflow. Keep it separate from food grade supplies and away from damp. Other fine dark powders look alike in a poorly labelled jar, so the label should name the element and the form.

How to tell it has deteriorated

The material looks like a fine dark powder and gives few visible signs of age, so the container is the better guide. A lid that no longer seals, fine dust on the neck and shelf, a cracked jar, a faded label and a missing date of receipt are the usual findings. Powder that has caked or darkened unevenly suggests moisture or a mix-up with another dark powder, and should be recorded as such. Nothing here suggests deterioration in the substance itself, only in how it has been kept.

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 We do not publish a drain or general waste route for any chemical.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 non-regulated or low hazard laboratory pack with compatible chemicals.

Unwanted powder must not be washed into a sink or drain, tipped into a general bin or put in a skip. It is not normally classified as hazardous, so 16 05 09 is the usual entry and a waste transfer note applies, though the producer classifies the waste. It stays a chemical waste and is described as one. Nobody should try to burn or dissolve it. Specialist collection is the only route. Record the form, the approximate amount and the state of the jar and label, and say if the powder has spread beyond the container.

Waste codes for Boron
Usual EWC code, laboratory stock16 05 09
Usually classed as hazardous wasteNo

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.

Common quantities

Usually held as: powder.

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

Questions

Is boron powder hazardous waste?

It is not normally classified as hazardous, so the usual code has no asterisk. It is still a chemical waste, so it needs an accurate description and specialist collection. It must not go in the general bin or down a drain.

How long can boron powder be stored?

No fixed life is set for it, and it gives few signs of age. Judge by the container: a tight lid, a legible label, a date of receipt and no spilled dust. Stock with no label or an unknown history should be recorded as unknown.

What should we write on the label of a boron jar?

Name the element, the form and the date of receipt. Dark powders look alike once a label has faded, so the name has to be legible. If the label becomes unreadable, do not guess at the contents or move the jar merely to relabel it. Record the remaining identification details and request specialist assessment where the contents cannot be reliably confirmed.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula B. EC number 231-151-2.

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