The explosive in the pagers was PETN, pedestrian and in use for more than a hundred years.
“PETN is a very powerful explosive material with a relative effectiveness factor of 1.66.[2] When mixed with a plasticizer, PETN forms a plastic explosive.[3] Along with RDX it is the main ingredient of Semtex.”
https://en.wikipedia.org/wiki/Pentaerythritol_tetranitrate
That effectiveness factor of 1.66 relates to TNT. So chemical analysis identified PETN? Per the above, could still be Semtex. In any case, a long way from M-80 flash powder - and the injuries even that can cause are well documented.
Of what relevance is it that the chemical has been in use for 100 years? It’s very powerful!