Mineral Content of Water From Public Fountains Along the Monon Trail in Central Indiana

Abstract

Background: The Monon trail is one of the most popular trails located in central Indiana that the public uses for various physical activities, such as cycling, jogging, and walking. Physical activity, especially in the summer, causes the body to dehydrate and lose some of its electrolytes via sweating (e.g., calcium, magnesium, potassium, and sodium). These minerals are considered important in regulating some of the body’s chemical and biological reactions. Therefore, water fountains are located along the trail. However, no study has thus far investigated the mineral composition of water provided along the Monon trail and how it compares with commonly used bottled water. Fluoride is added to tap water in many communities in the US for the prevention of dental caries (community water fluoridation). However, whether water provided by these fountains meets the recommended fluoride level by the CDC for caries prevention has not been established. Therefore, this study aimed to determine the fluoride, calcium, magnesium, potassium, and sodium contents from water samples collected from all water fountains along the Monon trail and to compare their mineral concentrations to commercially available bottled waters. As an exploratory objective, we also assessed the utilization of theses fountains by the users of the Monon trail. Objectives: The primary aim of this study was to evaluate the fluoride, calcium, magnesium, potassium, and sodium contents of water from public drinking water fountains along the Monon trail in central Indiana. The secondary aim was to compare the nutritional value of the collected water samples to that of commercially available bottled waters. An exploratory objective will be to study the utilization of these fountains by users of the Monon trail. Methodology: Two 50-ml samples of water from each fountain along the Monon Trail were collected. The fluoride concentration was determined using a fluoride ion-specific electrode (Orion #96-909-00). The calcium, magnesium, sodium, and potassium contents were determined by atomic absorption spectrometer, equipped with deuterium and cathode lamps at wave lengths of 422.7 nm, 285.2 nm, 589.0 nm, and 766.5 nm, respectively. Data collected from water samples were compared to those of bottled water available in Indianapolis, Indiana, using data from a recently conducted study. Mineral data of water samples were compared to recommended dietary allowances (calcium and magnesium) or adequate intakes (potassium and sodium) as established by the Institutes of Medicine. The utilization of those fountains by cyclists, runners/joggers, and walkers was also investigated by conducting an observational study at each water fountain during a one-hour period in mid- to late afternoon during a weekday and weekend. Data collection was taken twice, one month apart. The statistical analyses of the study were carried out using two-sided two sample t-tests at 5-% significance level. Results: The author identified seven water fountains along the Monon trail during the study period. Fluoride concentration was generally high (mean 1.01 parts per million [ppm]). Calcium concentration ranged from 45 ppm to 81 ppm (mean, 60.9 ppm) which was greater than those of magnesium (range, 4.8 ppm to 13.7 ppm; mean 8.4 ppm), sodium (range, 14.7 ppm to 78.1 ppm; mean 40.5 ppm), and potassium (range, 1.2 ppm to 2.2 ppm; mean 1.6 ppm). Overall, water fountains provided meaningful contributions to adequate intake of fluoride. However, the contributions to adequate intake of sodium and potassium, or to the recommended dietary allowances for calcium and magnesium were lower. Moreover, water from fountains was found to contain higher mineral concentrations than most bottled waters. Conclusion: Within the limitations of this study, it was found that water fountains are a valuable source of rehydration and essential mineral replenishment during and after physical activity, as they provide greater nutritious values than most bottled waters. Furthermore, it was found that F concentration in water fountains satisfies the standards needed to prevent dental caries.