Benzoyl peroxide (CAS 94-36-0): storage and disposal

A wetted paste in a tub is the usual laboratory form, while dental surgeries meet it inside a two part resin kit where it sits in one component and the activator in the other. That split exists for a reason, as amines start its decomposition, so never store loose laboratory stock near amine reagents. It needs a separate labelled space away from organic and reducing materials, and from acids and alkalis. Keep it cool and out of direct sunlight, away from any heater or autoclave, because heat is the classified danger. Inspect the lid and threads visually without touching or turning the cap. If dried residue, crusting or damage is visible, leave the container undisturbed and request specialist assessment. Dental kits can stay in their own box with the date on it.

Sound laboratory stock is a white paste or moist granular solid that clings together. What should worry you is a loose, dry, free running powder, or a paste that has shrunk away from the wall of the tub. White crust around the lid or in the threads means dried peroxide is sitting exactly where a turning cap creates friction. A bulging container suggests gas from slow decomposition. Dental resin components at low levels may simply harden or separate with age, so note the kit's expiry and condition. For tubs of laboratory paste, if the stock is old, undated or shows any of these signs, do not move it, do not open it, and get a specialist assessment.

Supplied wetted. Becomes heat and shock sensitive on drying.

This does not go through our standard collection route. It is arranged by manual enquiry, and never goes down the drain or into general waste.

Before asking for a collection, note the label wording, the size of the tub, any date and what you can see of the contents and lid without touching them. Say clearly whether this is a tub of wetted paste or dental resin kits, because a low level initiator in a kit is a very different item for an assessor. Both go by manual enquiry, as this substance is not quoted online, and a store assessment is recommended. Dry material may need a competent chemist in person or, with a warning sign, an explosives or emergency specialist. Dental practices would normally use 18 01 06*. It must never reach a drain, given its long lasting aquatic toxicity, and nobody should wet, open or move a dry tub.

Usually held as: wetted paste, dental resin initiator.

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.