Answer:
We arn't exactly given the first field, so for this reason, I will be listing some random fields and allowing you to choose from them:
1. Blood bank workers. The cross contamination from blood is quite a dangerous venture, hence why when a child gets a scratch, a teacher will tell them to wash their hands good and bandage said injury. Now, imagine how dangerous this could be at a blood bank? This could also be very dangerous if the blood is contaminated with illnesses unseen.
2. Farmhands. More specifically, the ones that deal with pest and herbicides. For obvious health hazards, people dealing with these chemicals often wear gloves, then clean their hands thoroughly afterwards to be safe.
3. Janitors. Obviously, dealing with different dirts, germs and other foreign objects would warrent one to clean their hands quite often.
These are three rather out-there fields, so I hope this helps!