[Urinary excretion of fluorides in children living around an aluminum smelter].

Aluminium industry discharges fluoride into the atmosphere and several studies have shown a slight but significant contribution to the intake of fluoride by children living around aluminium smelters. A monitoring system was set up in 1991, just before a new aluminium smelter came into operation in Loon-Plage, on the North Sea coast, to study the evolution of the urinary fluoride excretion in children around the plant. Every year, 250 children under 14 are sampled in infant clinics, nursery schools and a secondary school. Urinary fluoride excretion was assessed by a potentiometric method on a spot morning urine sample and information on exposure factors was obtained by questionnaire. Urinary fluoride levels decreased with age (r = 0.31) and were higher in children drinking a local bottled water rich in fluoride (geometric mean in mg per gram of creatinine: 0.69 vs 0.52) or taking fluoride tablets (0.82 vs 0.52). The mean urinary fluoride excretion in children did not vary significantly between 1991 (geometric mean: 0.70 mg per gram of creatinine, 95% CI: [0.64-0.77]), 1992 (0.68 [0.62-0.75]) and 1993 (0.68 [0.61-0.76]), even after adjustment for potential confounding factors and despite a moderate increase in atmospheric fluoride levels.