Year and years ago I designed a beryllium heat sink for some space hardware. A simple metal block, machined and then pickled.

We had a safety review and were required to do all the work in a special machining station with containment and filtration. To make long story short, I was standing outside when suddenly dust started blowing out. It took about 2 hours to determine it was just "dust" kicked up by a cooling fan. It was a very long scary 2 hours. Plus I was wet from being washed down.

That was scary but not really dangerous. We knew it was hazardous and had 2 levels of containment plus filtration masks. The real danger is when you don't have a clue. The best example is cutting edge aerospace where they were working with brand new materials. There are a lot of stories from 1950-1960's of technicians dying from strange illnesses after working on secret projects. The SR71 and Be-Al for example. More probable for sailors are the people who coat their lungs while spray painting IMRON without a respirator, cleaning toxic materials off your hands with solvents that are absorbed by the skin or the time the by-product of curing paint killed all the insect life in my garage. (Or that neat surplus or stolen stuff you bought on eBay)

Know what you are doing. I have enough friends that are sick right now.