Fluoride concentration of bottled water, tap water, and fluoridated salt from two communities in Mexico

AIM: To determine fluoride levels in bottled water, tap water, and fluoridated salt from two communities in Mexico. DESIGN: Stratified random collection of water and salt samples from Mexico City and Veracruz, Mexico for fluoride analysis. METHODS: Samples were analysed using a combination fluoride ion-specific electrode. Results were compared using Student's t-test and mixed-model ANOVA. Water fluoride values were compared by type, community and collection area; salt fluoride values were compared by community and collection area. RESULTS: 197 tap water samples, 133 bottled water samples and 20 fluoridated salt samples were collected. The mean (+/- SD) fluoride content for all tap water was 0.20 +/- 0.17 microg F/g (ranging from 0.01 to 0.88 microg F/g) and 0.24 +/- 0.24 microg F/g for all bottled water (ranging from 0.01 to 2.80 microg F/g). This difference was not statistically significant. When results were analysed by city, the difference between tap water samples was statistically significant. Ten bottled water samples contained more than negligible fluoride (ranging from 0.7-2.8 microg F/g). Mean salt fluoride content was 230.0 +/- 49.8 microg F/g, which was within governmental regulation levels. CONCLUSION: Some water samples had amounts of fluoride exceeding the maximum recommended levels. Salt fluoride levels were within regulation limits. Monitoring of fluoride content of both bottled and tap water is strongly advised.