Northern China is probably safer for avoiding hepatitis as long as you don't sleep around unprotected or eat uncooked dishes at greasy spoons that have unsterilized bowls and glasses/cups, etc.

Bacteria and viruses, etc tend not to survive in low temperatures.

My advice, cook for yourself and practice safe sex when in China or with low-class Chinese sex workers.

I suppose eating out at medium-sized eateries would be okay, though, if you can afford the extra meal cost. There you will be given sterilized bowls wrapped in cellophane.