[Urinary excretion of fluorides in schoolchildren of Lausanne and Geneva in relation to salt fluoridation].

Urinary excretion of fluoride and sodium and urinary flow were studied in 230 schoolchildren (average age: 11.1 years) in the following situation: in 1984 and 1988 in Geneva, 1 year and 5 years after the introduction of fluoridated domestic salt (250 mg/kg), and in 1985 in Lausanne, 15 years after the general introduction of salt fluoridation for this city and its surrounding canton (Vaud). Among consumers of fluoridated salt, the average excretion of F ion during morning and afternoon was 15.4 and 43.7 micrograms F/h, respectively, in Geneva (1988) and 26.4 and 49.9 micrograms F/h, respectively, in Lausanne (1985). Among non-consumers of fluoridated domestic salt, excretion values during morning and afternoon were 9.9 and 20.7 micrograms F/h, respectively, in Geneva (1988), and 18.4 and 26.1 micrograms F/h, respectively, in Lausanne. Between 1984 and 1988, an increase in fluoride excretion was observed in schoolchildren of Geneva. During approximately 10 night hours, 8.8 to 16.4 micrograms F/h were excreted in Geneva, but F-salt consumers in Lausanne excreted 25.8 micrograms F/h. Averages of sodium excretion varied between 80 and 144 mg Na/h at daytime and between and 81 mg Na/h at night.