Seasonal Variation of Fluoride Ingestion from Fluids in Kuwait

Method:  Using the cluster sampling technique, children aged 1-9 years were chosen from 2,000 randomly selected households in Kuwait. Questionnaires were then administered to their mothers to determine the children’s daily fluid intake during the summer and winter months. Fluoride concentrations in tap water as well as all brands of bottled water and beverages consumed by the children were measured, using the fluoride ion-specific electrode.

Result: The mean ambient temperature was 44^oC in summer and 22^oC in winter. In spite of this large temperature difference, the mean daily fluid consumption by the children was only about 10% higher is summer than in winter, being 1129 SD 302, 1372 SD 321, and 1599 SD 311 ml at ages 1-3, 4-6 and 7-9 years, respectively in summer, and 1149 SD 231, 1331 SD 271, 1538 SD 282, respectively in winter.  Mean fluoride concentration in tap water was 0.04 SD 0.02 ppm, and 0.28 SD 0.40 ppm in bottled water, but was much higher in hot and cold beverages (0.9 SD 1.4 ppm). Mann-Whitney U test showed that, daily fluoride intake was significantly higher in winter (range 0.03-3.50 mg/kg body weight) than summer (range 0.03-2.20 mg/kg body weight) among the children aged 4-6 and 7-9 years (p<0.05), and this was due to higher consumption of hot beverages in winter. In contrast, fluoride ingestion between the seasons was not significantly different (p=0.670) among those aged 1-3 years (a period when anterior teeth are mineralized), the range in winter being 0.02-0.82 mg/kg body weight, and in summer 0.01-1.10 mg/kg body weight.

Conclusion: Fluoride ingestion by children in Kuwait was significantly higher in winter than summer among children age 4-6 and 7-9 years, but there was no significant seasonal difference among the 1-3-years-olds.