WASHINGTON (AP) -- Federal regulators set a safety threshold Friday for the industrial chemical melamine that is greater than the amount of contamination found so far in U.S.-made infant formula.
Food and Drug Administration officials set a threshold of 1 part per million of melamine in formula so long as a related chemical isn't also present. They said they are continuing to analyze the results of tests on 87 samples of infant formula, but of the 74 samples analyzed so far, one had traces of melamine below the new threshold and another had traces of cyanuric acid, a related contaminant. None had both contaminants.
That's key because studies so far show dangerous health effects only when both chemicals are present, said Dr. Stephen Sundlof, FDA's director of food safety.
Both the safety level and the amount of the chemical found in U.S.-made infant formula are far below the amounts of melamine added to infant formula in China that have been blamed for killing at least three babies and making thousands ill.
"The levels were so low ... that they do not cause a health risk to infants," Sundlof said. "Parents using infant formula should continue using U.S.-manufactured infant formula. Switching away from one of these infant formulas to alternate diets or homemade formulas could result in infants not receiving the complete nutrition required for proper growth and development."
The agency had left the impression of a zero tolerance on Oct. 3 when it stated: "FDA is currently unable to establish any level of melamine and melamine-related compounds in infant formula that does not raise public health concerns."
The agency has not set a safety level for melamine if cyanuric acid is also present.
Separately, a third major formula maker told The Associated Press that in-house tests had detected trace levels of melamine in its infant formula.
The three formula makers whose products have tested positive for melamine or cyanuric acid - Abbott Laboratories, Nestle and Mead Johnson - manufacture more than 90 percent of all infant formula produced in the United States.
The FDA and other experts said the melamine contamination in U.S.-made formula had occurred during the manufacturing process, rather than intentionally. The U.S. government quietly began testing domestically produced infant formula in September, soon after problems with melamine-spiked formula surfaced in China.
Melamine can legally be used in some food packaging, and can rub off into food from there. It's also part of a cleaning solution used on some food processing equipment.
There is a gap between the concentration that the FDA detected in formula and the agency's estimate of how much melamine could contaminate food from the manufacturing process. The expected contamination from processing - 15 parts per million - is about one-tenth the amount that the agency has detected in infant formula. FDA officials have not responded to questions from the AP this week about how that gap might be explained.
The agency said it is continuing research on animals to see the effects of ingesting both melamine and cyanuric acid.