Is this safe to engrave on?

So do anyone know if the plastic ‘glass’ which comes in standard IKEA picture frames can be engraved with a laser.

Their website just says ‘polystrene plastic’ (it’s called the Ribba frame in the UK).

Is that safe to use???

Flame test it. Heat a solid copper wire in a propane torch, then get a bit of melted plastic on the wire and bring back to the torch. If it has green flame you have chlorine, a definite no go. There is a plastic, has a four letter name but I can’t remember it off the top of my head. It will cut UGLY, STINK, and the edges of the cut will be brown and not any where close to clean cuts… but at least the fumes will not kill you.

Info on the Beilstein test:

The green flame color, if observed, is produced by the presence of organic halides.

Unfortunately I dont have the frame or a blow torch or copper wire to test it.