Urinary Fluoride Excretion Among Children in Gaza Strip

Background: A positive association between prevalence of dental fluorosis and the fluoride level of groundwater wells supplying tap water (TW) has been detected in Gaza strip. The WHO recommends that urinary fluoride excretion (UFE) may provide an indication of body fluoride burden. The hypothesis of this study was that the UFE of children living in Gaza Strip positively correlates to fluoride concentration of used TW. Objectives: 1. To compare 24 hour UFE (mg F/day) of 4 year old children exposed to low (L), moderate (M) and high (H) fluoride concentrations in TW (<0.7, 0.7-1.2 and >1.2 ppm F respectively) in Gaza Strip. 2. To determine any relationship between 24 hour UFE and fluoride concentration in TW. Methods: 24 hour urine and TW samples were collected from 216 (4 years-old) children exposed to TW with L (n=81), M (n=72), H (n=63) fluoride. Statistical analysis was undertaken using ANOVA, Tukey's test and Pearsons Correlation with Minitab software (P<0.05). Results: Average fluoride concentrations (±SD) in L, M and H TW were 0.21(±0.15), 0.91(±0.13) and 1.71(±0.35) ppm F respectively. Differences in means of UFE of children (0.17, 0.25 and 0.38 mg F/day respectively) were statistically significant (P<0.0001). These values were lower than those reported by Ketley and coworkers (2004), but roughly similar to values reported by Warpeha and Marthaler (1995), which may be attributed to an increasing trend towards consumption of filtered water in combination with TW. A significant positive correlation was found between UFE and fluoride concentration in TW (r²=0.422, P<0.0001). Conclusion: Generally, UFE among children in Gaza Strip is low. The UFE can be a good marker for fluoride concentration of TW. Funded by: ORSAS and Newcastle University.