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Effect of Discontinuation of Fluoride Intake from Water and Toothpaste on Urinary Excretion in Young Children
Department of Paediatric Dentistry and Orthodontics, School of Dentistry, Federal University of Minas Gerais, Avenida Antônio Carlos 6627, Belo Horizonte, MG, Brazil
Department of Biochemistry, Piracicaba Dental School, University of Campinas, Avenida Limeira 901, Piracicaba, SP, Brazil
* Author to whom correspondence should be addressed.
Received: 23 February 2011; in revised form: 4 June 2011 / Accepted: 7 June 2011 / Published: 10 June 2011
Abstract: As there is no homeostatic mechanism for maintaining circulating fluoride (F) in the human body, the concentration may decrease and increase again when intake is interrupted and re-started. The present study prospectively evaluated this process in children exposed to F intake from water and toothpaste, using F in urine as a biomarker. Eleven children from Ibiá, Brazil (with sub-optimally fluoridated water supply) aged two to four years who regularly used fluoridated toothpaste (1,100 ppm F) took part in the study. Twenty-four-hour urine was collected at baseline (Day 0, F exposure from water and toothpaste) as well as after the interruption of fluoride intake from water and dentifrice (Days 1 to 28) (F interruption) and after fluoride intake from these sources had been re-established (Days 29 to 34) (F re-exposure). Urinary volume was measured, fluoride concentration was determined and the amount of fluoride excreted was calculated and expressed in mg F/day. Urinary fluoride excretion (UFE) during the periods of fluoride exposure, interruption and re-exposure was analyzed using the Wilcoxon test. Mean UFE was 0.25 mg F/day (SD: 0.15) at baseline, dropped to a mean of 0.14 mg F/day during F interruption (SD: 0.07; range: 0.11 to 0.17 mg F/day) and rose to 0.21 (SD: 0.09) and 0.19 (SD: 0.08) following F re-exposure. The difference between baseline UFE and the period of F interruption was statistically significant (p < 0.05), while the difference between baseline and the period of F re-exposure was non-significant (p > 0.05). The findings suggest that circulating F in the body of young children rapidly decreases in the first 24 hours and again increases very fast after discontinuation and re-exposure of F from water and toothpaste.
Keywords: fluoride; toothpaste; urine; drinking water
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Martins, C.C.; Paiva, S.M.; Cury, J.A. Effect of Discontinuation of Fluoride Intake from Water and Toothpaste on Urinary Excretion in Young Children. Int. J. Environ. Res. Public Health 2011, 8, 2132-2141.
Martins CC, Paiva SM, Cury JA. Effect of Discontinuation of Fluoride Intake from Water and Toothpaste on Urinary Excretion in Young Children. International Journal of Environmental Research and Public Health. 2011; 8(6):2132-2141.
Martins, Carolina C.; Paiva, Saul M.; Cury, Jaime A. 2011. "Effect of Discontinuation of Fluoride Intake from Water and Toothpaste on Urinary Excretion in Young Children." Int. J. Environ. Res. Public Health 8, no. 6: 2132-2141.