WASHINGTON -- Federal food safety regulators have set a safety level for the industrial chemical melamine in infant formula and are urging consumers to keep using U.S.-made formula.

Officials for the Food and Drug Administration said Friday that they've set a threshold of 1 part per million of melamine in formula so long as a related chemical isn't also present. The new threshold now defines as safe the concentrations that the FDA has found in its testing so far.

The safety level is far below the amount of melamine added to infant formula in China that has been blamed for killing at least three babies and making thousands ill.

"The FDA has been collecting and analyzing samples of domestically manufactured infant formula for the presence of melamine and melamine-related compounds," the FDA said on its Web site. "To date, FDA tests have found extremely low levels of melamine in one infant formula sample and extremely low levels of cyanuric acid in another. The levels were so low that they do not pose a health risk to infants:"