Urinary Fluoride Concentration And Excretion In Adults 3 Months After The Introduction Of Fluoridated Salt In A Public Catering A. Schulte (1)*, R. Gräber (1), C.H. Kasperk (2), M. J. Koch (1), H.J. Staehle (1) (1: Department of Operative Dentistry, 2: Clinic of Endocrinology, University of Heidelberg, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany, Fax: +49-6221-565074) To date investigations have demonstrated a suboptimal F-intake if fluoride is added only to domestic salt with a concentration of 250 mg/kg salt. A distinctly higher F-intake can be gained if F-salt is used also to fabricate food (i.e. bread). Only very few data are available about the effects of the use of F-salt in a public catering on the urinary F-concentration and F-excretion of adults. In April 1999 the canteen for the employees of the medical and dental faculty of the University of Heidelberg has started to prepare all meals with F-salt. A prospective study to monitor for 3 years the urinary F-concentration and F-excretion of persons going regularly to this canteen has started in March 1999. 260 volunteers (study group 200 persons, control group 60 persons) are taking part in this survey. Before and 3 months after the introduction of F-salt in the canteen each study participant delivered a 24h urine sample. The urinary F-concentration of the samples was determined by means of a F-electrode. The following mean F-concentrations and F-excretions (±standard deviations) were computed:     F-concentration F-excretion   at baseline after 3 months at baseline after 3 months control group (n=60) 0.41±0.20 mg/l 0.49±0.26 mg/l 27.9±14.6 µg/h 26.3±13.3 µg/h study group (n=200) 0.41±0.22 mg/l 0.55±0.36 mg/l 29.6±16.3 µg/h 33.8±17.9 µg/h   In the study group a statistically significant increase of the mean F-concentration and F-excretion was found (p<0.001, Wilcoxon-Test) but not in the control group. In average the participants of the study group had taken 42.1 main meals in the canteen. From the first results of this study we conclude that eating main meals of a public catering prepared with F-salt contributes to a distinct improvement of F-supplement after a relative short period of time.   This study is supported by the German Federal Health Authorities (Bundesministerium für Gesundheit). Grant No.: 227-42265-49.