Working in measurement automation (in C - LabVIEW is for wheenies).
Radiation sources, black soot on the ceiling (especially near the vents), vacuum pump leaking oil and vibrating at close to 80 dB, one mercury spill, and other things come to mind, but you get the idea. I'm lucky I only had a temporary rash (I hope).
Since then I've moved to code less and make more experiments (science works, bitches!) but the environment is pretty much the same. Did you know it takes an Act of Congress to build a new government building?
I love my job.
All life evolves by the differential survival of replicating entities. -- Dawkins