The contribution of drinking-water to total dietary intakes of selected trace mineral nutrients in the United States
Abstract
Mineral nutrients in drinking water contribute to total dietary exposure. However, there has been little effort to quantify this contribution. An examination of dietary data from the United States, in combination with U.S. Environmental Protection Agency (U.S. EPA) monitoring data on mineral contaminants in drinking water, provides an opportunity to evaluate the importance of drinking water as a source of mineral nutrients in the United States. Data for chromium, copper, fluoride, iron, manganese, selenium, sodium, and zinc have been evaluated for this study. Only copper and fluoride make major contributions to the diet for large segments of the population. In both cases, a substantial portion of the exposure is due to factors other than the presence of the mineral in source water. Copper is contributed by leaching from pipes, and fluoride is added to many systems in the United States because of fluoridation practices. As drinking water concentrations of minerals approach regulatory or guidance limitations, their contributions to total dietary exposure increase. However, only a small portion of the population is exposed to the higher drinking water mineral concentrations. The combination of the 95th percentile intake from foods with levels at or near the U.S. EPA regulatory or guidance limits for drinking water does not exceed the dietary tolerable upper intake levels. However, there are sensitive populations, such as individuals with Wilson’s disease (copper) or hemochromatosis (iron), who may need to manage their risk of exposure to minerals in drinking water. [The opinions expressed represent those of the authors and do not necessarily reflect the opinions of the U.S. EPA.]