[Arran]

Mike;
That was one factor I forgot about, rodent feces and urine, well the urine is less of a health hazard, but very corrosive, the feces can be a bad thing. A friend of mine ended up in bed sick for a month after inhaling dust from dried up rat and racoon feces.
Another one you run into is selenium in dry metal rectifiers, not so much of an issue from handling, but if they short and go up in smoke you had better leave the room and ventilate it for an hour. I find that they often become useless long before they short out anyhow, the voltage output, and current level drops with age.
Regards
Arran