Urinary fluoride excretion in 4-year-old children in Sri Lanka and England.

Urine was collected over 24 h from children aged 4 years in Sri Lanka and England. Fifty-three children were from Dambulla, Sri Lanka, and 44 from Newcastle, England, both localities receiving drinking water containing 0.8-1.1 mgF/l. Urine volume was measured immediately after the 24-hour collection and samples of the collection from each child were frozen for transportation prior to 'blind' analysis in one laboratory for fluoride content. The mean 24-hour urine volumes were 504 ml (SD 198) in Sri Lanka and 449 ml (SD 196) in England (p = 0.17). The mean F concentrations were 1.19 ppm (SD 0.63) in Sri Lanka and 1.02 ppm (SD 0.42) in England (p = 0.12). The mean weights of fluoride excreted were 0.55 mgF/day (SD 0.30) in Sri Lanka and 0.42 mgF/day (SD 0.19) in England (p = 0.009). The distributions of weight of fluoride excreted were also dissimilar in shape between the two countries. The extent to which these small differences in fluoride excretion in urine reflect differences in fluoride intake needs to be investigated.