I'm glad that you guys are so cautious, but (this is MY opinion) I feel that it is unnecessary to worry so much about that small amount of medicine. I have used Ich meds in the past and had my hands all in the tank, although not for a few hours after it.
If you haven't noticed, EVERYTHING causes cancer!!! When I was working construction, I had to tear out some walls that had asbestos (sp?) in them, because it causes cancer. When I washed my aquarium sand, the label says the dust from silica sand causes cancer. There are counteless other "substances" that cause cancer. Now I'm not trying to say that you should be foolish in how you handle things, for instance: for the walls with asbestos (again, sp?) -I tryed not to breath the dust when we tore it off (had no masks). When I washed my silica sand - I wore a mask. When I use meds that are toxic, in any way, I try my best not to get it on my skin or ingest, etc. But when you dilute it into the water, it is such a minute amount that probably (again, MY opinion) wouldn't affect you unless you did this your for a living, like handling sick fish in aquariums for a living.
Now, what I do when I get Ich is:
-quarantine if possible.
-Remove ANY carbon/chemical removers
-raise temp to about 82 degrees
-heavily airate the water (with air pumps)
-add 1TBSP salt per 5 gallons water (for sensetive fish maybe 1tsp/5-10 gallons) Dilute in water, then add slowly.
-30% to 50% water changes 1/day (best) or at least 1/3 days.
-Vacuum gravel THOROUGHLY ever water change
-Use a DIATOM, MICRON filter, or U/V Sterilizer if possible during treatment.
-continue treatment for minimum of 2 weeks (up to 4 = safe)
-(ICH lifespan @ 70 degrees= ~3wks, 80 degrees= ~5 days!)
Visible symptoms should stop within 4 to 5 days (tops)
If they persist or return:
-Use Quick Cure (malachite green + Formalin)
-Add dose (recommended) daily
-50% water change daily
-do all steps from above advice
to remove medicine:
-FIRST do 50% water change, then....
-add carbon to filter
-after 1 week: remove carbon and do 50% water change
-should be clear***