The current upper limit consider safe to consume with regularity, is "4 milligrams of fluoride per liter of water" The CDC sets the recommend fluorination leve

The current upper limit consider safe to consume with regularity, is "4 milligrams of fluoride per liter of water" The CDC sets the recommend fluorination levels are 0.7 mg/L, more than 4x lower than the amount considered safe to consume. So you would need to consume over 20L of water (think 10 2L soda bottle worth). I couldn't personally physically do that.