Total Fluoride Intake and Urinary Excretion in German Children Aged 3–6 Years

There have only been few investigations comparing total fluoride intake and the fluoride proportion excreted in urine in pre-school children. In addition, the results of available studies are conflicting. Total fluoride intake was assessed in 11 healthy children aged 3-6 years on 2 consecutive days and urinary fluoride excretion was determined. The duplicate-diet approach was used for the assessment of fluoride intake from solid and liquid foods. Fluoride intake from toothbrushing was calculated as the difference between the amount of fluoride in the paste put on the toothbrush and the drinking water (fluoride concentration 0.25 mg/l) used for rinsing vs. the fluoride amounts recovered in the toothpaste spat out and in the rinsing water. Use of fluoridated domestic salt and/or fluoride tablets was recorded. The children's intake of fluoride from food averaged 202.5+/-116.2 microg F/day. They swallowed an average amount of 273.9+/-175.6 microg F/day when brushing their teeth. Daily fluoride ingestion from all sources totalled 930.7+/-391.5 microg or 53.0+/-21.4 microg/kg body weight. On average 51.5% of the fluoride ingested was excreted in urine. The wide interindividual variation makes it necessary to evaluate the urinary excretion rate for fluoride in larger study populations with varied fluoride exposure.