Went thru a similar with BeCu a year years ago. Granted, pure Be is highly toxic and should never be handled with bare hands, and of course any machining of it is very hazardous unless you are set up for it. However, pure Be is very rarely used for anything. The amount of Be in BeCu typically found in machined parts is 2% (Alloy 25). And skin contact poses so little a hazard it requires no special precautions. We had one guy on a little 18n quick-turn who was convinced he was having a problem with contact dermatitis from the particle in the coolant in the machine he was running and handling the wet parts.
So we hired and independent Industrial Hygienist out of Dallas to come down and have a look. They took coolant samples from his machine and all the others where BeCu had been machined, they hung sniffers around all the burr hands' necks to take air samples where they worked. I was actually a little concerned about their exposure, myself. They spent all day with air motors and flap wheels, scotchbrite discs, files and sandpaper....all things that made fine particles (especially compared to a lathe). Their hands were black and green by the end of the day. Of course they washed before eating and smoking, but still.....some of it had to have gotten into their bloodstream, in my opinion. After a week, all the tests were done and we were nervously waiting on the results, under threat of a lawsuit from the lathe operator.
He was 100% clean. The coolant (one of the Trim products, iirc) was not a solvent for Be, and any particulate matter was too heavy to stay in suspension, so his skin tests were negative. My burr guys were, to my amazement, also clean. All well below OSHA exposure limits. We had no problem with machining BeCu. As it turned out, we had Brush-Wellman, NGK, and one other mfg of BeCu material furnish us with all the appropriate safety documentation during this period, and it all pointed to the hazardous operations the actually DO exist when working with it. We didn't do any of them. Most were more closely connected with the creation of the alloy to begin with, so it was well upstream of us in the first place. If you melt it, yes the fumes are hazardous. If you weld it, yes, the fumes are hazardous.....I forget the actual size of the particulate that was the threshold for concern, but it was on the order of smoke size . And I know of no machine shops that deal with it at a hazardous level. IMO, the concern is much overblown. I spent literally days researching and in meetings about it, and that is my opinion.
I love machining the stuff actually. Not lately, but I had picked up several jobs for other shops who got scared of it, from all over the country. It's expensive, but I like it. I have a good friend who is a major distributor of it up in WI. In fact, he owns a smelter in Italy where it is made.
Oh the operater was allergic to the coolant, so we moved him to a machining center.....no more problem. He quit not long after.