Styrene (CAS 100-42-5): storage and disposal

In a school prep room it tends to be a small bottle at the back of the flammables cabinet, bought for polymer work and then forgotten. That cabinet is the right place, with oxidisers, oxidising acids and corrosive stock kept elsewhere. Warmth uses up the inhibitor faster, so avoid radiators, sunny benches and hot upper shelves, and use only a spark-free refrigerator if it is chilled at all. Write the arrival and opening dates on the bottle, because date checks are the only practical way to judge a substance whose inhibitor cannot be seen. Organ damage from repeated exposure and the suspected risk to an unborn child are good reasons to keep handling rare and to stop buying more than a class needs.

Good stock is a thin, clear, free-running liquid that may be very slightly yellow. Nobody needs to tilt the bottle to find out: a syrupy layer or a hard plug at the bottom, visible from the outside, shows polymer has formed and the inhibitor has been used up. Thickening is the warning sign. Polymerisation gives off heat, so a bottle that is warm with no reason, or one that has bulged, is more serious than a merely old bottle. If it is old, undated or shows any of these signs, do not move it, do not open it, and get a specialist assessment. It is also a class C entry on peroxide former lists, and any peroxide testing is for competent staff.

Once the inhibitor is used up it can polymerise and give off heat, which can build pressure in a closed bottle.

This can form peroxides as it ages, especially after opening. Age and the opened date matter more than appearance, so a container with no opened date should be treated as old.

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 We do not publish a drain or general waste route for any chemical.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 flammable laboratory pack with compatible chemicals.

Packing places it among compatible flammable organics, but a bottle that has started to set is no longer an ordinary item in that group, so describe its state. Say whether the contents are thin, syrupy or solid, and give any dates from the label. A solid block of polymer in the bottle is still listed as styrene waste, because unreacted monomer may remain. Harmful to aquatic life with long lasting effects, it must never go into a sink or drain, nor into a general waste bin or a skip, and nobody should try to treat or harden it first. Specialist collection is the single route. A surplus bottle in sound condition is much simpler to deal with than one left another few years.

Usually held as: neat.

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.