No RDA is currently stipulated. A safe upper limit for children has been set at 0.5mg per kg per day. If you don’t have fluoridated tap water, ask your dentist about giving fluoride drops to your children.
There is much controversy surrounding fluoride supplementation. Substantial research shows that fluoride can be very toxic when added to drinking water or toothpaste and can lead to a higher incidence of hip fractures, cancer and fluorosis with liver cell damage and discolouration of teeth.
Research also shows that fluoride supplementation doesn’t prevent tooth decay at all as originally thought. The biggest concern seems to be the inability to control intake when fluoride is indiscriminately added to drinking water. Most fresh foods contain small quantities of fluoride. The FDA doesn’t regard fluoride as an essential micronutrient at all.