It is really hard to definitively say, except by noting that there have been widespread health problems noted only with people involved in smelting, casting, machining and otherwise working with metallic Beryllium.
I used to live in Tucson, AZ where one of Brush Wellman's beryllium facilities was located. They made the news for a long time because of health problems with their workers. Interestingly, some folks worked there for decades with no ill affects even though they were directly involved in fabrication. Others developed severe health consequences. Those others included directly exposed fabrication workers, secretaries and other workers in the offices with no direct exposure, and people living near the plant who had even more indirect exposure. There are currently theories that beryllium disease only affects a part of the population that has a particular genetic component. Since that component is not yet identified, no one can say if they are susceptible until it is too late.
One of the few papers on BeO that isn't well hidden behind a paywall mentions that BeO is a carcinogen when injected into the veins of rabbits, and when sprayed into the trachea of rats. It also finds that no carcinogenic affects were noted in several other species including guinnea pigs, chickens, cats, and dogs. Obviously they couldn't run human experiments so the effects in humans are unknown, but this lines up with genetic variability in susceptibility to beryllium problems.
The message remains. Don't do obviously stupid things and then sleep well at night.