Did a bit of googling and found this :-
"Selenium dioxide is the major compound produced when a selenium rectifier is overheated. It can cause severe burns to the mucous membranes and severe respiratory tract, skin, and eye irritation. It can also promote allergic reactions with the skin. Fortunately it is not considered a carcinogen.
Another fortunate thing is the awful smell which gives it away. If you smell something really rotten, like decaying onions and garlic, coming from your equipment, it is best to leave the area immediately, opening some windows on the way out. Allow the selenium dioxide vapours to dissipate for several days before you go back - you will not want to go back very soon anyway!""
Wish I could have a chat with my lecturers about this !!! Fortunately though , I've never been in near proximity to a blown sel rec.
Looking for the above I also came across this nasty :-
"Beryllium oxide (BeO) or beryllia, found in some power transistors, transistor and valve bases, VHF ‘ceramic’ transmitting triodes and klystrons, is very nasty stuff (if you inhale just a few micrograms, you could be dead in a week or two). Luckily, if you avoid filing, sanding, or smashing the stuff, you are quite safe in handling it – large chunks are safe, micro-sized particles are dangerous. "
Glad I read about that , I have this habit of 'dismantling' things to satisfy my curiosity !!
