Effect of Discontinuation of Fluoride Intake from Water and Toothpaste on Urinary Excretion in Young Children

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.

Effect of exercise on fluoride metabolism in adult humans: a pilot study

“…In the present pilot study, the length of time for a ‘wash-out’ period was determined based on the previous studies in children and adults which have reported a rapid decrease in circulating F in the body of young children in the first 24 hours after discontinuation of F from water and toothpaste 28 , in contrast to a relatively constant UFE in adults being reached in one week following fluoridation of water 29 .…”

A comparative study of fluoride ingestion levels, serum thyroid hormone & TSH level derangements, dental fluorosis status among school children from endemic and non-endemic fluorosis areas

“…Hence, it is evident that the analysis of fluoride in body fluids besides drinking water is highly relevant and necessary for understanding potential health implications (Martins et al 2011). The results of the present investigation indicate that improvement in the health of the children would likely be achieved if management strategies incorporate emerging knowledge to address fluoride toxicity in the individuals, even if residing in non endemic fluoride areas.…”

A systematic review and meta-analysis of 24-h urinary output of children and adolescents: impact on the assessment of iodine status using urinary biomarkers

“…Due to the wide age range of participants of the included studies, studies were grouped into three groups according to the age of the participants; 2–5 years (17 studies) [ 26 , 28 , 36 , 43 – 45 , 50 , 51 , 54 – 57 , 60 , 62 , 68 , 72 , 74 , 75 ], 6–12 years (20 studies) [ 25 , 30 , 35 , 36 , 45 – 48 , 52 , 54 , 58 , 59 , 61 , 63 – 66 , 71 , 76 , 81 ] and 13 to < 19 years (12 studies) [ 25 , 26 , 29 , 36 , 49 , 53 , 54 , 63 , 65 , 67 , 69 , 81 ]. These cut-points were chosen based on the WHO criteria for assessing population iodine deficiency, which defines school-aged children as between 6 and 12 years of age [ 6 ].…”