The Food & Drug Administration (FDA) said yesterday that “trace” amounts of melamine had been found in a sample of U.S.-made baby formula.  The FDA would not release the name of the formula or its manufacturer, and has maintained that the amount of melamine found poses no danger.

According to CNN.com, last month, the FDA set the safety threshold for melamine at 2,500 parts per billion for foods other than infant formula. The agency said it did not have enough data to set a safety threshold for infants.  The amount of melamine found in the sample of infant formula was less than 250 parts per billion, CNN.com said.

In the U.S., melamine is not allowed in human or pet food, although the FDA has approved melamine as a “food contact substance.”  An FDA source interviewed by The Wall Street Journal speculated that the melamine contamination was the result of contact with the chemical during processing and packaging.

Melamine is an industrial chemical that is used to make plastics, fertilizer, and fire retardants.  Melamine is a renal toxin that can cause kidney stones and acute renal failure if ingested in large amounts.

In recent years,  a number of Chinese manufactures have been involved in scandals involving melamine tainted food. In 2007, melamine-tainted wheat gluten, used as an ingredient in pet food, killed at least 16 dogs and cats, sickened thousands of others and led to one of the biggest pet food recalls in American history.

In China, melamine-tainted formula has sickened over 50,000 children this year, killing at least four. The melamine was apparently added to milk powder by manufacturers to make it appear that their watered-down baby formula was more nutritious than it really was.

Melamine has since been found in dozens of foods around the world that had  been made with Chinese-manufactured milk powder.  More than 13 countries, including the U.S., discovered products made with melamine-tainted ingredients.  The list of tainted food  included  candy, yogurt, frozen desserts, biscuits, instant coffee, milk tea products, and other beverages.

Since the Chinese infant formula scandal broke, the FDA has been detaining imports from that country that contain dairy ingredients for further testing.  The agency has also been testing U.S.-made baby formula, although U.S. manufacturers do not obtain ingredients  from China for formula sold in the U.S.