Human milk is very low in sulfate (5 mg/L), and even though an average value for infant formula products (both milk- and soy-based) was found to be 13 times higher than that in human milk (66 mg/L), these levels of sulfate are still lower than those in many sources of drinking water (Hoppe et al., 1998).

Surveys of sulfate intake from food and beverages are currently not available. The Third National Health and Nutrition Examination Survey has not estimated sulfate intake directly. Indirect estimates of sulfate intake can be calculated from the intakes of sulfur-containing amino acids. Table 7-4 provides estimates of sulfate intake that would be derived from metabolism of cysteine and methionine. The estimates provided in the table thus do not include sulfate from food, beverages, or drinking water, nor that derived from organic sulfur compounds other than methionine and cysteine.

Adult Human Data. Osmotic diarrhea and loose stools have been reported with high intakes of sulfate consumed in water (Backer, 2000). Such adverse effects are usually short term, but they may be more severe in infants. The U.S. Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) collaborated in a 1997 study to determine whether high levels of sulfate in drinking water would cause diarrhea or other gastrointestinal disturbances in infants and in adults categorized as “transients” (i.e., those experiencing an abrupt change in water sulfate concentration from low to high) (EPA, 1999a). The study involved 105 adult volunteers from Atlanta, Georgia, including CDC and EPA employees, who were randomly assigned to one of five possible sulfate exposure groups. Sulfate concentrations (from sodium sulfate) tested in drinking water were 0, 250, 500, 800, and 1,200 mg/L. Participants were given water for 6 days. The water provided for days 1, 2, and 6 of the 6-day study contained no added sulfate, whereas the water provided for days 3, 4, and 5 contained added