I think the Mercury hazard (from the mercury switches) may have been overstated.
Mercury is a metal in its liquid form at room temperature and can be poisonous if you ingest it or inhale it in its vapor form--but that's not likely since it boils at about 365 deg. F, so first you would have to heat it. It will not harm you to handle it; but that is not recommended; still, you're not going to die or grow three heads, etc. (lol). Because it is very heavy it will sink in water and most other substances. It is not soluble in water and soap has no effect on it.
The main environmental concerns are groundwater contamination and ingestion by marine life, which is why the EPA doesn't want it in landfills, etc. Unless you are using it to smelt gold, make glass or some other industrial process, it's not likely that you're going to come into contact with it's vapors.
The bottom line: Be aware of its toxicity and pay attention to what you are doing, otherwise use ordinary precaution and will be fine. Any Mercury that has leaked will have sunk to the bottom and likely been thrown out and/or pumped out with the wash water.