Continuing Occurrence of Melamine and Its Derivatives in Infant Formula and Dairy Products from the United States: Implications for Environmental Sources

A total of 52 infant formulas and 42 dairy products, including milk, yogurt, cheese, and butter, as well as bread purchased from Albany, New York, were analyzed for melamine and its derivatives (cyanuric acid, ammeline, and ammelide). Sigma Melamine (sum of melamine and its three derivatives) was found in infant formula, milk, yogurt, cheese, butter, and bread at median concentrations of 4.8, 7.9, 5.1, 17, 4.2, and 7.5 ng/g, respectively. Median Sigma Melamine concentrations in infant formula collected in 2008 (9.4 ng/g) were significantly higher than those collected in 2018 (2.7 ng/g). Similarly, there were significant differences in Sigma Melamine concentrations between powdered (median of 2.3 ng/g) and liquid forms (9.0 ng/g) of infant formula. However, no significant differences in Sigma Melamine concentrations were found between milk-based (5.0 ng/g) and soy based (2.3 ng/g) or between organic (4.4 ng/g) and nonorganic (4.8 ng/g) forms of infant formula. Cyanuric acid was the major derivative found in all products analyzed (68-83%), followed by melamine (7.0-21%), ammelide (2.5-10%), and ammeline (0-6.0%). The average daily intakes of Sigma Melamine by U.S. infants via formula and adults via dairy products were 0.687 and 0.032 mu g (kg of body weight)(-1) day(-1), respectively. Our study suggests ongoing but low-level contamination of food products marketed in the United States with melamine and its derivatives.