SAN FRANCISCO (MarketWatch) -- The Food and Drug Administration has found one positive sample of U.S.-made infant formula containing melamine "at very low trace levels," the Wall Street Journal reported in its online edition Tuesday. The agency also found melamine in a few samples of nutritional supplements and medical supplements, all made by the five U.S. manufacturers of infant formula, the newspaper said. However, the melamine detected was at low levels and is believed to be the result of contact with melamine during the processing or from packaging, the Journal reported. Stephen Sundlof, director of the FDA's Center for Food Safety and Applied Nutrition, told the newspaper that the melamine found in U.S.-made products is not a cause for concern from a health standpoint.