Urinary Fluoride Excretion By Children 4–6 Years Old In A South Texas Community by Ramon J. Baez, Martha X. Baez and Thomas M. Marthaler

This study evaluated urinary fluoride excretion by school children 4–6 years old who were livingin a south Texas rural community that had concentrations of fluoride in drinking watersupplies generally around the optimal level. We took supervised collections of urine samples inthe morning and afternoon at school, and parents of the participating students collected nocturnalsamples. We recorded the beginning and end times of the three collection periods andthen determined the urinary volume and urinary flow for each of the periods. We measuredurinary fluoride concentrations and calculated the urinary excretion rate per hour. The childrenhad breakfast and lunch provided at the school, where the drinking water contained1.0–1.3 milligrams/liter (mg/L) fluoride. Fluoride concentrations in the tested household watersupplies, from wells, ranged from 0.1 to 3.2 mg/L fluoride. The children’s average urinary fluorideconcentrations found for the day were similar to those for the night, with means rangingfrom 1.26 mg/L to 1.42 mg/L. Average excretion was 36.4 μg/h in the morning, 45.6 μg/h inthe afternoon, and 17.5 μg/h at night. The lower nocturnal excretion rates are easily explainedby low urinary flow at night. Based on the 15 hours of urine collected, the extrapolated 24-hour fluoride excretion was 749 μg. In conjunction with similar studies, the data from thisstudy will help in developing upper limits for urinary fluoride excretion that are appropriatefor avoiding unsightly fluorosis while providing optimal protection against dental decay.

Link : http://www.scielosp.org/pdf/rpsp/v7n4/1926.pdf