How much sodium fluoride should the average person get each day?

5 - 10 grams: The lethal dose for a 154 lb human is estimated at 5–10 g. I don't think you could eat enought toothpaste to kill yourself.

Toothpaste, water: You should brush with a ada approved Fluoride toothpaste at least twice a day, preferably three times a day. This along with drinking optimally fluoridated municipal city water (1 ppm) will give you the proper amount of fluoride. If you have a lot of decay or decalcification, your dentist can prescribe toothpaste with more Fluoride than otc.