Pers,
To take your concern seriously, I think the key issue is whether Beryllium poses any risks in the context that M will be using it (such as aerosolization of trace quantities as the speaker is used).

We all put our research and faith in products we use every day. I will put my faith (though, admittedly, without any specific knowledge) that Meridian has done its research in this regard, and has determined that no material risk is posed.

That said, it's always possible that in working with a driver manufacturer, Meridian may not have been aware of negative aspects of the material not related to it's audio characteristics. If that is the case, I would hope that they see this thread and do whatever research is required.

Living room: 818v3, Parasound A23+, Maggie 1.6
A/V room: 861v8, DSP7200SE L/R/C, 4x DSP320 surrounds, ID41 + Roon, UHD722, Prime+PS