A problem about formality

Is my food on the plate that has dropped to the ground? if so then I wish to have food which has not been in contact with the ground.

Food that has been in contact with the ground may have germs that will make me sick if i eat this food.

even if there is no food on the plate I wish it to be as clean and germ free as possible.

Please wash my plate if it has been on the ground before serving my food on it.

Always wash your hands before serving or handling food made for other people.

I would pick it up and say sorry, then ask if you may take another plate/bowl or whatever you dropped. It depends where you are though. Usually, at very formal dinners you eat at a table. If it's more of a cocktail party, it's all finger foods (you take straight from a big plate and pop it into your mouth).

thank you
I have learned some konwleage from you !thank you !