Answer:
Soak it in dishwashing liquid and bleach every day before you use it. Slate cheeseboards arnt the best because they have to be washed well before use otherwise the cheese may carry a diesese. But if anyone in your family gets a miner ache anywhere you should see them to a dotor to check for back injury.
So make sure you bleach it if anyone feels a little sore or sick. I do this alot and it always works really well. There are usually only a few backaches and eye aches