Objective: To explore the exact relationship between daily total intake of fluoride and children’s intelligence quotient (IQ).
Methods: Wamiao village (severely endemic fluorosis area, drinking water fluoirde was 0.57-4.50 mgL) and Hinhuai village (non-endemic fluorosis area, drinking water fluoride was 0.18-0.76 mgL-1) in Shong County, Jiangsu Province, were selected for this study. All 8-13 year old students in two village primary schools were recruited as subjects in this study. Children’s IQ, drinking water fluoride in children’s household shallow well, daily total intake of diet and water, and fluoride level in indoor and outdoor air were investigated, and the daily total intake of fluoride was calculated. The children were divided into 5 subgroups according to the daily total intake of fluoride which were <1.00, 1.00-1.99, 2.00-2.99, 3.00-3.99, ?4.00 mg (per person d)-1. Children’s IQ and the rate of IQ <80 in the subgroup were calculated.
Results: Children’s IQ in Xihuai village was significantly higher than that in Wamiao village (100.41 ± 13.00). Children’s IQ decreased and the rate of IQ < 80 increased according to the increasing of daily total intake of fluoride. There were significant dose-response relationship between the daily total intake of fluoride and the children’s IQ (y = -3.519x + 103.310), and the rate of IQ <80 (y = 5.779x -1.347).
Conclusions: High level of fluoride intake may affect the development of cerebrum for infant and adolescent, and would result in lower IQ.