Fluorures et eaux minérales : Influence de la minéralisation de l'eau sur l'élimination urinaire des fluorures chez l'adulte sain

Fluoride and mineral water: Influence of the mineralization of water on the urinary excretion of fluoride in the healthy adult

Laboratoire d'Hydrologie et d'Hygiène - Faculté de Pharmacie 28, place Henri-Dunant - BP 38 - 63001 Clermont-Ferrand Cedex

Résumé

L'objectif de cette étude randomisée, réalisée en cross-over chez l'adulte sain, est d'évaluer l'influence de la minéralisation de l'eau sur la biodisponibilité des fluorures, d'une part après une prise unique de 500 ml d'une eau minérale bicarbonatée sodique carbo-gazeuse fortement minéralisée renfermant 6 mg/l de fluorures (CFM) et d'autre part après une prise unique de 500 ml d'une eau plate faiblement minéralisée (PFM) artificiellement dopée en fluorures afin d'obtenir une concentration de 6 mg/l.

Il a été observé dans ces conditions, que l'élimination urinaire des fluorures augmente rapidement chez tous les sujets. 47,4 ± 4,0 % de la dose ingérée est éliminée au cours des 12 heures suivant la prise d'eau CFM et seulement 38,7 ± 1,7 % après la prise de d'eau PFM. Dans le cas de l'eau CFM, une rapide alcalinisation des urines est observée, ainsi qu'une corrélation significative entre la quantité de fluorures éliminés et le pH urinaire (p < 0,05).

Abstract

Wakes in the main source of fluoride exposure. Endemic fluorosis have been observed in India Mediterranean countries and Africa. Fluorosis have been noticed in heavy drinkers of mineral water rich in fluoride, with chronic renal failence. The aim of this randomized cross over study, performed with healthy adults, was to evaluate the influence of other minerals of the water on the bioavailability of fluoride. Fifteen volunteers, eight men and seven women, 24 to 60 age (mean age 36,2 years) were studied. Food, medecine, tooth - paste rich in fluoride and calcium were forbided. Two mineral waters were used, in one hand asparkling and highly mineralized natrium carbonated water (CFM) containing 6 mg/l of fluoride (Vichy water) on the other hand a weakly mineralized water (PFM), artificially, doped to 6 mg/l of fluoride. The pharmacokinetics of fluoride, sodium, potassium, calcium, magnesium, chloride, urinary pH, creatinine and density were studied. After the simple ingestion of 500 ml of both tested mineral waters, the urinary fluoride excretion increased rapidly in all subjects. 47.4 ± 4.0% of the fluoride intate were eliminated in the twelve following hours with the CFM water and only 38.7 ± 1.7% with PFM water (p< 0.05). Statistical analysis showed that the other parameters did not change significantly. Urinary pH was tested before ingestion and every hour, a rapid alkalinization of the urines was observed with the CFM water after 6 hours. During the first five hours, urinary pH after ingestion of both tested mineral water was significantly different. Various studies have demonstrated than fluoride absorption in solution passive (intestinal absorption), rapid (40-60 min.), important (80 to 90%). It has been demonstrated than fluoride elimination is moosthy urinary. It depends on urinary pH. Reabsorption decreased and fluoride elimination increased, on the kidney with alkaline pH. Urinarylevel of fluoride is an index of fluoride in man. There is an influence of food, gastric secretion, and physico-chemical capacities of waters on fluoride bioavailability present in mineral waters. Fluoride tubular reabsorption seemed to be inversely correlated with urinary pH. This renal mechanism avoid and excessive concentration of fluoride in human.

It is concluded, on one hand, from a general point of view, that the activity of an element at the same concentration in a mineral water depends on the presence of the other elements, and on the other hand no fluorosis were noticed in healthy subjects in Vichy area.