Film of the 1960’s was certainly ‘Safety Film’ and 35mm was often marked as such outside the sprocket holes. I don’t think the explosive stuff was around post WW2. Of more concern is colour shift. The dyes used in colour slides are not that reliable over time. It’s a very good reason to digitise them now and correct them where necessary. I’ve got some commercialy produced Kodak slides that (since 1973) have realy shifted, to the extent that I would not show them again. Mind you, they were not wonderful when new. B&W film and slides (especially home processed) of course don’t shift with time.
I’ve found a good write up on film base at: https://www.nedcc.org/assets/media/documents/Preservation%20Leaflets/5_1_FilmBaseGuide.pdf