Purpose: The objective of this study was to verify the use of nails as biomarkers of chronic fluoride (F) exposure from the diets of children living in communities with negligibly or optimally fluoridated water.
Methods: Fifteen 2- to 6-year-old children living in Bauru-São Paulo (fluoridated) and 15 lifelong residents of Itápolis-São Paulo (nonfluoridated) participated in the study. Fluoride concentrations in nails and duplicate diet were analyzed with the electrode, following hexamethyldisiloxane (HMDS)-facilitated diffusion. Data were analyzed by student's t-test and linear regression (P < .05).
Results: Mean fluoride concentrations ([microg/g) in fingernails and toenails of Bauru children were 3.56 +/- 1.3 and 2.81 +/- 1.29, respectively, and for Itápolis children 2.29 +/- 1.25 and 1.58 +/- 0.59, respectively. The differences between Bauru and Itápolis children, as well as between fluoride concentrations in fingernails and toenails, were statistically significant. The estimated fluoride intake from the diet was significantly higher for Bauru children (0.55 +/- 0.61 mg) when compared to Itápolis children (0.09 +/- 0.06 mg). A significant positive correlation was found between the mean of fingernail and toenail fluoride concentrations and estimated fluoride intake from the diet (r = 0.57).
Conclusions: This study's preliminary data suggests that fingernails and toenails may be used as biomarkers of chronic fluoride exposure from the diet. Additional studies are necessary to determine the predictive values, sensitivity, and specificity of this biomarker so that nails are used to differentiate children at the age of dental fluorosis risk and who live in communities with negligibly or optimally fluoridated water.