Most packages with beryllium oxide have been abandoned long ago, beryllia being replaced with aluminum nitride.

Because aluminum nitride is not as good as beryllia, packages with beryllia have survived for some special applications, like military, aerospace or transistors for high-power radio transmitters.

Those packages are not dangerous, unless someone attempts to grind them, but their high price (caused by the difficult manufacturing techniques required to avoid health risks, and also by the rarity of beryllium) discourages their use in any other domains.