Laser printers bugger you up?

I have known glass particles to stay in a body for >50 years, they come out rounded off however.

Nope. Mineral wool dissolves. Glass does not

Read again

AIUI white asbestos particles also dissolve in the lungs over a few years, and don't remain long enough for cancers to develop, unlike the fibres of blue or brown asbestos. The latter two are mostly used for thermal insulation rather than fibre-board, although for a while after WW2 they were also used in both, so you can't be certain without analysis which your old shed is made from.

Not sure about glass fibres. A lot will depend on composition. Glass used for making glass fibre (E-glass) won't have the same composition as container or window glass, but I wouldn't like to say which is the more soluble in a lung environment.

There's this:

Note that asbestosis isn't the same as mesothelioma, the cancer very specific to asbestos fibres. AIUI asbestosis is a general deterioration of the lungs, broadly comparable to silicosis, farmers' lung, black lung in coal miners, byssinosis in cotton-mill workers, and many other lung deterioration diseases caused primarily by over-exposure to a specific dust associated with a particular occupation. None of them nice, all debilitating to a greater or lesser extent, all best avoided by taking appropriate precautions when handling, but they're not the same as mesothelioma.

PS IANA medical expert!